Wealthy means they have money saved. This money generates them money so they can cover a lot of their expenses and have security that if their circumstances change they won’t be in financial trouble. The good thing about wanting them to become wealthy is that they get to define what wealthy means to them. There is no expectation that they have to earn a certain amount of money (although I do want them to be able to afford to move out when they are in their 20’s!).
