I have seen American athletes with bigger egos, plus, Bolt had said before the Olympics that if he repeated what he'd done 4 years earlier he was going to consider himself a legend. He kept his promise, unlike some of our athletes. Most pundits/former sprinters (Maurice Green, Michael Johnson etc) said he could not do it. He did, and he can consider himself a legend. Plus if we base it on achievement, he is a living legend.
He is faster than our runners, that hurts, but, no track athlete currently can command the interest of 2 billion people (it could have been more if Costas' network did not do what it does best.. not show what people want to watch).
Bob Costas can go back to producing 3rd rate tear jerking pseudo journalistic trash that he produces for nbc sports network while interviewing and fawning over young female gymnasts and I may add young female swimmers too.