Since 2011, Groupon has lost $730 million, and Zynga has lost just over $1 billion. Twitter has been in business for 10 years and went public in 2013. Since then, the company has lost $2 billion.

Why can't modern tech companies both grow and turn a profit at the same time?

Conventional companies try to find new uses for capabilities they already have. Transformers look at what the market needs and then go build it, hiring new people and/or taking people off other jobs.

Nvidia's self-driving-car business grew out of a long-standing relationship with auto companies. Car guys used Nvidia chips for computer-aided design, then used Nvidia supercomputer chips to do crash simulations. When the car guys started thinking about autonomous vehicles, Nvidia leaped at the chance to help them solve the problem.

Most startups flame out or just muddle along. Your chances of spotting a unicorn, pre-horn, are incalculably small. But if, knowing that, you still want to toss aside your cushy job, at least listen to corporate vets who have made the transition.

A startup job is an investment, after all: Venture capitalists may wager money, but you're staking something more precious - your time. And unlike VCs, you can't spread your risk by betting on a bunch of companies at once. Start with TAM. That's 'total addressable market,' and if it's not big enough, there's no point in talking.

If your plumber or pool installer or local appliance store uses HubSpot software, HubSpot may be holding information about you without you even knowing it. We figure we're safe when we use online services. We figure we can trust the people who run them not to snoop on us. I used to believe that. I don't anymore.

Some law firms now use artificial intelligence software to scan and read mountains of legal documents, work that previously was performed by highly paid human lawyers.

Is any job safe? I was hoping to say 'journalist,' but researchers are already developing algorithms that can gather facts and write a news story. Which means that a few years from now, a robot could be writing this column. And who will read it? Well, there might be a lot of us hanging around with lots of free time on our hands.

These days a typical netizen has dozens of online accounts. If you really want to be safe, you need to have a different password for each one, and each password needs to be incredibly complicated, with a mix of capital letters, symbols, and numbers. Who can keep all that stuff in their head?

Fingerprint readers require special hardware, and a lot of people find them creepy and don't want to use them. Smart cards and tokens can be lost or stolen.

What if people could use the Internet to create a new kind of money, one that didn't involve governments and central banks and could be used anonymously, like cash?

With digital attacks becoming rampant, the computer nerds who work for the good guys to thwart such incursions have become the new Navy SEALs - elite commandos who can carry out sophisticated operations on the battlefield of cyberspace.

Content is supposed to be king. But in the world of electronic devices, Apple seems to be placing the crown on its own head, apparently believing that its iPad and iPhone are more important to customers than the books, movies, and music they store on them.

In the world according to Apple, content is just a bunch of digital bits, easily copied, nothing special.

Some people are using landline connections and dial-up modems to call ISPs in other countries and get onto the Internet. Still others are using satellite connections.

Mesh networking is an old idea. Oddly enough, the low-cost XO Laptop built by the 'One Laptop Per Child' organization - the so-called $100 laptop - was designed with built-in mesh networking. The idea with the XO machine was that many kids using those laptops would be out in rural areas without reliable Internet access.

The chance to interact with big shots is drawing scads of aspiring entrepreneurs to Quora, along with venture capitalists and other Valley players.

With the iPod, iTunes, iPhone, iPad, and iMac, Apple is the most powerful tech company in the world. It's also the No. 1 music retailer in the U.S. and among the top sellers of online movies, too.

The iPod wasn't the first MP3 player. Nor were the iPhone and iPad the first in their categories. The real reason for the success of these devices - the true unsung hero at Apple - is the iTunes software and iTunes Store. Because Apple provided them, it wasn't just selling hardware.

In the 2010 holiday quarter, Apple reported $26.7 billion in revenue, up 70 percent from a year before. That means it's nearly as big as IBM, which did $29 billion in the same quarter.

Apple is very, very good at almost everything it does, and that includes corporate communications.

Apple is on fire, delivering smash hits across its entire product line. It's hard to think of another company that has ever been on such a roll.

Early on, Android phones were pitched as kind of ersatz iPhones, devices that could do most of what an iPhone did - but were available on carriers other than AT&T, a relatively horrible network that was the biggest source of complaints about Apple's transformative device.

Android phones are sold by dozens of hardware makers, the biggest being Samsung, Motorola, and HTC. There are lots of different form factors. Slider phones. Phones with keyboards. Big screens, small screens, midsize screens.

I used to be a pretty hard-core iPhone fan. But over time, I grew more and more frustrated with the lousy service on AT&T. My iPhone simply could not reliably make and hold a phone call. Not just in New York and San Francisco, where I spend a lot of time, and where AT&T's service has been notoriously bad for years.

For the most part, cookies aren't dangerous. They were created so advertisers could get a better idea of who you are and what you're interested in, so they could send you ads you're more likely to find relevant.

'Do not track' probably won't spell doom for online advertisers. But it will put the burden on them to explain to consumers what targeted advertising is and why it's good for them. They'll have to come out of the shadows; they'll have to be honest with people. What a radical concept. I'm all for it.

PayPal, which was founded in 1998, may be the closest thing to a global currency that has ever been created. Based in San Jose, California, the company operates in 190 markets, sending and receiving payments in 24 currencies on behalf of 90 million active members.

What needs to change is the nature of advertising itself. That business hasn't really evolved since the days of Don Draper.

There's no special technological wizardry involved in what Groupon does.

One way Groupon hopes to gain an edge is by using software to learn about its members so it can deliver more relevant offers: my wife will get the manicure-pedicure deal, but I'll get an offer on fly-fishing lessons. The key now is execution - delivering great customer service and keeping everybody happy on both sides of the transactions.

Since the beginning of the internet era, it has been pretty widely accepted that when you join an online service, whatever data you put into it belongs to you.

Google views Facebook as a threat to its business and has been trying to launch a social-networking service to compete with it.

Remember the early days of the Net, when everything was going to be open and free, and we were all going to share information in a techno-utopia? That was great until people realized that their user data could be turned into gold. Now there are billions at stake, and nobody is playing nice anymore.

Can anyone create an enduring business on the Web, where it's easy to build new companies, and when survival depends on the whims of fickle users? The big lesson of 'Digg' may be simply this: if someone offers you a ridiculous amount of money for a company that wasn't that hard to build, don't think twice. Take the money and run.

Social gaming is not something Zuckerberg could have imagined back when he was creating Facebook in his Harvard dorm room in 2004. The change began in May 2007, when Facebook announced it would let outside developers create applications that run on top of Facebook.

Nobody ever imagined how quickly the Android mobile-phone platform would take off - not even Andy Rubin, the Silicon Valley engineer who created it.

Android is the kind of runaway smash hit that techies spend their careers dreaming about.

In addition to making Android available for free, Google also lets phone makers change the code and customize it so that an Android phone made by, say, Samsung has a different user interface than an Android phone from Motorola.

I often wonder what the world would be like if more companies were like Apple.

Fixing mistakes is one thing. Apple's bigger strength has been its ability to keep improving hit products.

The iPod Touch is basically an iPhone with the phone part taken out, which is fine - since making calls is the one thing that the iPhone doesn't actually do very well.

Carrier networks were originally built for connecting phone calls. Now they're getting swamped with bandwidth-hogging data applications. Keeping up will require huge investments. Who's going to pay for that?

Net-neutrality proponents howled when Comcast started throttling traffic from BitTorrent, a bandwidth-hogging program people use to swap video files. The Federal Communications Commission sided with the open-Internet folks, ruling that Comcast could not selectively choke off traffic.