Maybe you can bet NFTs against other forum users, a lot for them has NFTs and like gambling, so, maybe if you find the right users and the right match to bet you could find a scrow who hold the NFTs while the match is going on.
The problem about betting the NFTs is the price of the NFT, the fact that I can put that NFT on a market and ask for $1 million that doesn't mean that's the real NFT cost.
That’s a good idea. Anyone who wants to do escrow? The bet against my NFT (number #777) would be about 0.22 eth. Since it’s a first and a fun one, I suggest doing it for free but open to all suggestions.
Escrow is you pr main problem on this kind of bet since they typically charge on percentage basis or high fixed amount in BTC. This is why P2P betting in huge amount is not advisable unless you are against reputable member that will honor bets.
I think Zenland can handle escrow like this since they escrow through smart contracts which your NFT can be sent.
The transaction fee might be costly if you will do the transaction in Eth blockchain.