That's not entirely true. We're not dumb animals. We can consciously decide when one's own self-interest has been served adequately, and then focus some energy on helping others who need it. You can do that micro, giving some back every day or week in small ways. Or macro... many or even most ruthless industrial/tech barons turn philanthropist and spend their later years giving their money away. Or in the case of Elon for example, trying to save humanity by establishing extra-planetary colonies. Whether you agree that needs to be done or not, you have to respect the guy's overall motives.

We can all think of experienced great leaders from a variety of fields who we wish would run for office or take political jobs. Most don't, because they don't want to immerse themselves in the cesspool. Gen Mattis as SECDEF is a good example of an exception, and I know as fact that he did it out of a sense of duty to maintain a stable military command & control system.