Dyna-Soar should never have been abandoned in the first place. Neither should the X-15.
...
Blame the Soviets. Those programs were dropped to pay for the space race.
#5,7,8 The Dyna Soar was abandoned due to the cost of repairing the pilot.
I think it cost $6 million : )
https://www.youtube.com/watch?v=bGO57y4td-c