I'd say that getting caught up in a stupid craze is one of the most important learning experiences that a kid can have. One day everybody suddenly starts talking about a new thing, and it seems like it's going to be around forever, so you put all your pocket money into getting as much of it as possible. Then, a few months later everybody starts talking about some other new thing and you're left with no money and a whole lot of stuff which you now realize was worthless all along. Suffer that a few times in childhood and you'll be more immune to it in later life. Spend $30 on football cards when you're eight and you'll be less likely to spend $500,000 on suddenly-inflated real estate when you're 35.

The lesson doesn't work if your parents actually buy you the cards (rather than giving you pocket money and watching with bemused tolerance as you spend it all on slips of cardboard), though, like this kid's parents apparently did.