NASA’s biggest issue over the last 35 years is that it became a political target. It is really hard to do long term design when your mission changes every 4 years along with a different budget. NASA should have a budget that is only reapproved every 30 years and should not have to worry about outside influence from a president dictating its mission.

Them and the military. There's only one other major airplane military contractor, Lockheed, and then a couple of smaller companies.

The 6th gen fighter program, Next Generation Air Dominance, is supposed to be a family of planes where one human plane controls a small squadron of drones of various models. The Air Force gave contracts for two of those drones to some of the smaller companies beside Boeing and Lockheed. They tend not to come right out and say these things, but a good guess as to why is that they don't want to have those two be the only options.