As long as we are trying to determine causes of people's success, we should consider their location in time.

Imagine if Erdos had been around before Euler? Who's to say that he wouldn't have discovered some or more of what Euler discovered. The earlier discoveries were the easier one, the low-hanging fruit.

If I went back in time it would be easier for me to make some ground breaking discovery, like pythagoras theorem. But today, I need to be smarter and more clever than centuries of mathematicians to add something new to our collective knowledge of the universe. All of the easy problems are solved :(