My relatives regularly gave me cash for holidays and birthdays. And if your parents ever gave you cash for anything it's easy enough to not spend all of it and

My relatives regularly gave me cash for holidays and birthdays. And if your parents ever gave you cash for anything it's easy enough to not spend all of it and save some. I probably usually had >$300 in my bedroom as a teenager (and more saved in a bank account). Also the kid can lie about what they spent it on. Or steal their parents'/siblings' money. Mistakes that lead to important life lessons.