There isn’t an “enough” threshold. It depends from person to person, basically, if you can do something and you get paid for that, then you do it. It’s even easier to accept doing it if whatever you need to do is easy for you.
So in the case of an actor, “we’ll pay you a ton of money to sell tobacco and gambling” can be very tempting because it’s easy for them. Also it gives them more exposure and fame, and you may think they already have enough but no. If they don’t take it someone else will and they will no longer be top N.1.
Sorry kid but people don’t make money to increase their moral understanding. They make money to afford living a certain lifestyle. For most people, it’s just covering basic needs. Maybe to help their families do the same. But for those who already have all that covered it’s just to gain more, and you are right it’s really sad they don’t care how. They should care.