The Warren Buffet Billion Dollar Challenge is an online thing I belIeve. Not sure which state would regulate it. Maybe Warren Buffet's state of residence? Who knows? I don't even know if it costs to enter the challenge. If it doesn't, then technically it isn't gambling.
Professor,
Warren Buffet's challenge is NOT gambling. Gambling requires both that it be a game of chance AND that there be a fee charged to enter the contest. Being there is no fee it is not gambling.
Gambling should be legal, in general. I would prefer the government not be involved in legislating vices.
As a national issue, gambling is in general legal (as long as you pay taxes on the winnings). It is regulated by the states, NV is the least restrictive in what it permits.
The question posed is "should there be NATIONWIDE pools"? I stick with my response that doing so would be impractical and probably illegal. But if a state wanted to organize something thru the state lottery commission that would work.