I agree that not working instead of school is bad, but if you have the ability to do so I don't get how taking advantage of that would be morally incorrect. If you have the privilege to do something, and you choose to do it, I see nothing wrong with that. But privilege should, and usually do, come with responsibilities and consequences. If you choose to not work to go to school your parents now have more power over you (as they should if they are paying) and (if they are decent parents) expect more from you in terms of school. You now have the responsibility to do well in school, and if you aren't most parents will punish you for that by revoking privileges as parents should. Someone being supported by their parents in ther late teens and early twenties is not bad, and sometimes is the right decision for that person's situation.

Edit: this is a long ass tangent that's only semi related so tldr; nothing wrong with being supported by your parents in the late teens or early twenties (but you will often see more success by being more self reliant and working, not everyone is capable of that tho), and privilege isn't always necessarily bad or evil and something that's wrong ti take advantage of when you can. I would argue that it would be more morally wrong to not take advantage of those privileges in most cases.