No not really. Polymarket collects fees which are simple and deterministic. Bets on outcomes are tokens on the blockchain and can be "split" ($1 into YES/NO outcome tokens) and "redeemed" (YES & NO outcome tokens into $1). Placing a bet is simply a market order on a plain ol' central-limit orderbook for these tokens. The only house there is maybe the market makers, which isn't a house. If it were a type of "house", then NYSE/NASDAQ has a house too.