Goldman Craps no Sachs and other such companies ???

I dont understand the rationale behind such huge bonuses. They are stealing money - sort of. I would say when they consider bonus as a way of retention, then i think the problem can be solved easily if govt restricts the maximum bonus to realistic values. So if someone gets 300K bonus in GS, that person cannot go to any other place for want of better bonus as there is a limit. So now people will value the company for what it is and they will be loyal to it. For now its loyalty to money and thats what they see, after doing an MBA , is that what they are taught ? What sort of ethics are they working on ?