You have to pay millions because other people on Wall Street are paying millions thus the best talent goes there.
What you're implying is that we should have top-down wage controls (i.e. a command economy) or bottom-up wage controls (i.e. collusion). The first is an idea which is seductive, but historically a failure. The second is illegal under our current rules and should remain illegal lest you want every department store to collude to pay their workers minimum wage + 1 cent.
I'd argue that if the government (us) hadn't bailed everybody out, the firms would fail and then they'd make $0. If a small firm could afford to pull in some of the unemployed traders, more power to them, but then it's an employer's economy and the salaries (and bonuses) would be more reasonable. The market would more or less work itself out (though it could be painful in the short term).
What you're implying is that we should have top-down wage controls (i.e. a command economy) or bottom-up wage controls (i.e. collusion). The first is an idea which is seductive, but historically a failure. The second is illegal under our current rules and should remain illegal lest you want every department store to collude to pay their workers minimum wage + 1 cent.