How is a $70,000 prize "so huge"?
Sinquefield cup

The prize fund is $170k for 4 players.
You can see the link to the tournament in this post:
http://www.chess.com/forum/view/general/st-louis-sinquefield-anyone-going

The World Championship winner gets somewhere around 1.5 mil $. That indeed is some money. But if you compare it to how much a football star earns, it's very little.
Prize money is so huge. If chess had a big boom in past also?