The elastic range of steel is what makes it unlike any other commonly-used metal. If steel didn't spring back after being flexed, it wouldn't be steel, and every steel bicycle frame/fork, suspension/cantilever bridge and super skyscraper on the planet would snap and come crashing down. Google "tacoma narrows" to witness how far steel can flex before fatigue finally occurs.
The learned art of the cold-set is to deflect and approach the yield point carefully, while not exceeding the yield-point-deflection to obtain the final position desired upon spring-back; not a novice procedure. The smooth bend of a fork's rake is typically a cold-set process, isn't it?