So I asked a friend who's familiar with gambling laws across nations (works at an Indian casino, but before that a Vegas casino) and they said that likely its because of a few things.
1: It's a lottery that you 'pay into' via a monthly subscription. The more mules = more chances makes this a possibility.
2: Some states have very direct laws regarding lotteries/contests; they're worded so that no minor period can collect a prize in a lottery or contest, even if its not a 'tangible' possession.
There's a couple others they thought might apply but those 2 are the ones that usually catch people when entering into contests. It's not so much about getting sued for damages, it's that a state/national govt could 'investigate' and levy a fine based on whatever law is on the books, which may or may not force SE to provide information on how many under gambling age people are playing for the purpose of giving/avoiding a huge fine, which they can't do.
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