Teamfight Tactics is introducing a new Collector’s Bounties system that is aimed at the wealthiest of players. To roll the Collector’s Bounties, you’ll need to cough up 450 Treasure Tokens (approximately $17 USD). In order to guarantee you hit the Prestige skin you’ll need to roll at least 30 times.
Because in our society we very much need money and gambling sells itself by making you believe you’ll get money. Cosmetics in games has no such issues.
EDIT: as long as you can’t sell them for money a la CSGO.
If that was the only reason, nobody would care about vulnerable people as long as they’re not dirt poor to begin with.
Decent gambling laws are supposed to protect people with addiction problems.