Just that really. Someone I know was just talking about it, she's childfree, and has a good disposable income and does it every year.
I just found it a bit weird, I get that her parents have more money but she can afford it herself. She kind of looked down on me that I didn't do it and said a clanger about my parents "must not want to go on holiday with me." She's an only child.
A bit different if you are broke and your parents do it as a one off to treat you.