The problem is that is the nature of bonuses. Succeed and get a bonus. To mitigate the risks we need a system where instead of bailing out, we let the companies fail. Banks should close. People should lose money. People should be cautious of investing on shaky grounds.
The only need is credit unions and financial institutions who are FORBIDDEN from behaving in certain risky ways. People will store their money in these banks/unions which are "stable" so nobody loses their savings. If you invest, you invest, and all is well because you knew the risk, or should have known. These crashes will actually balance themselves out as people's money won't just dissappear. And those responsible will be out on the street. Well... maybe not, the big wigs probably have their money safely tucked away.