Some people have low self esteem, either because of their nature, or their relationship with their family, or their peers.
Then, in order to feel better/ superior, some of these people buy a lot of expensive things, or try to become very rich, so others treat them nicer.
But these psychologically unhealthy people have a sort of hole insides themselves that can't be permanently satisfied, they always want more. This is greed.
Greed makes them want more and more, no matter how much others are suffering, or how much their work is really worth.
These greedy people (e.g. Some execs and musicians) can be detected by their display of wealth. They'll buy a mansion, or an expensive car, instead of a regular house or car.
The people around them think: Hey, I work just as hard, or more, and I can barely pay my necessities and you're buying unnecessary things to flaunt your money? Time for you to get less money.
So taking money from these people is not "theft", but actually justice.