Maybe it was competition in the 1980's with the soviets trailing, but with the fall of the USSR in 91' the competition was over. Through the 90's and 2000's NASA and the DoD kept pushing new exploratory technology and increasingly advanced and technical engine designs.
SpaceX was notorious for eschewing experienced rocket scientists and grinding out work from novice engineers, but I think it is fair to say they still benefited from the pool of experience they did tap into.
