One of the big first computers was called SAGE, which was a missile defense, the first missile-defense computer, which was, like, one of the first computers in the history of the world which got sold to the Department of Defense for, I don't know, tens and tens of millions of dollars at the time.
An awful lot of successful technology companies ended up being in a slightly different market than they started out in. Microsoft started with programming tools, but came out with an operating system. Oracle started doing contracts for the CIA. AOL started out as an online video gaming network.