This is a non-custodial (Trustless) platform, meaning they never take possession of your crypto. When you place a bet, the coins are sent to a contract, where the bet is decided and settlles in the same transaction. If you win, you are paid immediately.
Polygon is an Ethereum sidechain where the tx fees are about a penny per tx. They allow wagering in the mainnet coin of the same name, USDC, and their house coin (ROLL). The first two are available via Binance and major exchanges, ROLL is available via Sushiswap/Apeswap, etc.
I have put $200k+ through, and am slightly ahead. The bets are decided via a neutral 3rd party on every bet (Chainlink Oracle).