I don't think it's a scam, all rules (including creator cut) seem clear from the start. People know what they're in for, they're not being tricked in any way.

Unless as you say the creator wins the pot themselves

Just because the rules are "clear", doesn't mean there isn't an element of scam.

For example: https://en.wikipedia.org/wiki/Dollar_auction

The Monty Hall problem has very simple rules, yet most people don't fully understand what's happening. That one even fools many professional mathematicians.

Even a spin machine in a casino has clear rules, with the house cut printed in large letters on the side. It's still a scam, carefully engineered to take advantage of every mental vulnerability that it can.