Plus there was a lot of "low hanging fruit" from the war time that was yet to be "productify", as we say today.

Radars, computers (Enigma crushers), lasers, many less visible inventions that had a great impact in say, materials science - those barrels had to be durable, planes lighter and faster, etc this allowed do build fancier stuff. Whole nuclear industry and its surrounding.

Another factor: cold war, there was incentive to spend money if only there was some chance to win some advantage.