There were schools of computer science, accredited universities, that taught it heavily (one of the 3 lab intro to programming languages next to c++ and python, and allowed to be used through the entire program at mine). A 1/3 of graduates of some of these places got jobs in it, because they were reliable and well paying jobs.

And then the industry swapped to C++. This was not a DoD mandate, this was companies like boeing trying to pay their engineers 1/3 to 1/2 less by paying for C++ devs (starting salary for ada devs was 90-140k, starting salary for c++ devs was 60-180k according to exit statistics). They of course eventually learned that good C++ devs are actually more expensive than their old Ada ones. Not that they bothered to hire good c++ devs.