SpaceX's reusable rockets is from SpaceX if I understand it correctly but...

Obviously musk didn't build the rocket or planned the rocket but that is not the point.

Nasa had plans for reusable rockets but for the longest time, the financial risk of development was higher than the value of reusable rockets. SpaceX didn't care about the financial risk because they needed thousands of satellites for the most brain dead idea ever, starlink and because Elon is bad with money (Twitter...)

So SpaceX was "successful" because they were crazy enough to run 2 extremely dangerous projects.