This is like Onehash, they're also a mutual betting bookie. I thought when you have said about investors, you're looking for funding to the entire platform that you're building but little did I know that it's already built.
The structure that you're asking the investors is to simply bet and increase the volume day by day. You didn't mention how the investors will make from that structure.
I would like to make profit-sharing agreements with any investors. Fees on betting are low (0.10% to 0.5%), but with good volume there should be money coming in.
It is also a very liquid investment. Investors hold the private keys to their money and can cash out their stablecoins at any time.