I think the coolest part about it, is you don't necessarily have to match an investor with a gambler. But you can match gamblers with gamblers. For example if I was willing to bet 1 BTC @ 2x and Bob was willing to bet 1 BTC @ 2x, and both willing to pay a 1% house edge. The casino could match the two bets, and take a risk-free expected value of 0.02 BTC.

Or someone could put in "order" to do a 100 BTC gamble with 0 house edge, etc. I think it'd be pretty cool to just operate it like a bet exchange, taking and matching orders.

The part I don't like, and is dealing with the edge cases around disconnecting. e.g. where one party doesn't or can't or won't reveal the seed that created their hash. You'd probably have to do something like they have X period of time to reconnect and provide it, or the bet is decided against them. But it's going to be a pretty bad user experience for anyone when that happens, and you'd likely need a ban or reputation system to ban gamblers/investors who did that too often.