They (or their parents) are being forced to spend large sums of money just to be locked into this card ecosystem, so that they can play with their friends. The company designs these cards with certain appealing colors and characters, and charges a hefty premium for them.
And anyone who can't afford to buy the cards (or is threatened with copyright violations if they make their own) is left out of that community.
And every year I'm forced to buy a new set of cards just to keep up with friends. Clearly they've engineered some addictive property into these cards to produce that very effect.
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Is this similar enough? Or maybe it's the NFL or NBA or Nike shoes, or little league hockey, that we should cut/paste in there?