Greed, one of the seven deadly sins, is both toxic to society and intrinsic to human nature. It can’t be ended or “stopped” -- but it can be regulated, which is the goal of good tax policy.
In the late 1970s, the US Supreme Court, under the guidance of Justice Lewis Powell, decriminalized political bribery: specifically, in 1976 they legalized bribery of politicians by the morbidly rich and in 1978 they legalized bribery of politicians by corporations.
With this newfound power to buy politicians and to shape American policy, CEOs and the very rich could have done anything. They could have ended childhood poverty. They could have made sure every American had a quality education at no cost. They could have given every American free, quality healthcare like in other developed nations.