It happened because the public is stupid. Pure and simple. It's democracy. Tell people they have a chance to win the lottery—that they can only dream of someday being in the top 0.01% fab-extra-mega-rich if we allow the top 0.01% to remain fab-extra-mega-rich—and they will happily vote to send all of their wealth of any kind, labor, material, anything, right into the slot machine.
Capitalist ideology wins again. Nobody wants to regulate the economy because then they can't exploit the same holes to their own "advantage." Never mind that it's no advantage at all. Everyone is busy trying to climb the ladder, and is convinced that if they climb a little harder, they will be one of those few to reach the top. And damn everyone else.
Once it all collapses, the public will of course cry out for somebody to "do something." What they really mean is "it isn't fair—I didn't win!"
The American people deserve exactly what is going to happen to them now, and they're going to get it because they voted for it.