And if you were in any doubt before, this lesson is now exemplified by the holder of the highest office in the land and approved by popular vote. The rewards of acting ethically are, unfortunately, sometimes only personal. This must be a hard environment to raise children in, given the examples they see around them.
Parent here: it takes a lot of discussion, but it's a great time to talk about the reality of evil and villains. My kids are on the good side, or at least I like to think so ...
This argument may focus too much on the category of external rewards.
I might well be kidding myself or self-justifying, but I believe internal rewards are at least as important. Some materially successful people are deeply unhappy.