I think a lot of people say these grandiose things about smart people because they don't want to consider that they simply spent 30+ years doing little but their work/passion and are simply very good.

Feynman was a genius, but he dissects his own accomplishments and you can see how if you only knew this, this, this, and that, plus a few different methods of integration, it would have seemed obvious to you too.

tl;dr we do our heroes a disservice when we hold them in too high esteem, because we discount their very human, and very costly, accomplishments.