How did SpaceX accelerate their development so fast ? What took NASA decades to achieve in terms of high tech rocketry SpaceX achieved in less than half the tim

How did SpaceX accelerate their development so fast ? What took NASA decades to achieve in terms of high tech rocketry SpaceX achieved in less than half the time. What are the factors ? The people Elon hired were ex NASA ? Where did the working knowledge come from ?I don’t think I found the answer anywhere on the internet.