Jason Alexander was interviewed by Matt Lauer on the Today show, 5/21. He was asked if he would have left "Seinfeld" if his money-related demands were not met by NBC. His response was a very serious, straight-faced "yes".
He explained in detail that the reason for demanding such outrageous salaries (he even described the amount as such himself) was because NBC had refused to give him (and the others) a share of the syndication profits.