The Laffer Curve is a unicorn-y concept that seeks to explain the rate of taxation at which revenues will fall because earners either move away or decide to earn less (or cheat more, I guess).
If I were a tax scholar interested in this concept, I would be taking a good, hard look at the current behavior of top-tier professional athletes. Boxing is particularly interesting because it allows a participant to choose where he performs. If you are a pro golfer or tennis player, you might be inclined to skip a particular event because of a tax situation, but you generally need to play where the event is happening. A top-ranked boxer, meanwhile, can fight where he gets the best deal.
Which is why it's interesting to read that Manny Pacquiao will probably never fight in New York -- primarily, says promoter Bob Arum, because of the taxes he'd have to pay.