Another Option
On another option that hasn't been explored much, perhaps we should have an option where investors can choose to be based on amount wagered instead of amount won - at say a substantial reduced amount - example would be at 40% house 'risk cut'.
The problem with this is that those investors aren't risking anything at all. When the house needs coins to pay out a winner, these investors aren't going to give up their coins. They may as well not even bother depositing their coins, because we're just going to put them into cold storage and then give them back, with interest.
My point is, what do such investors bring to the table? What use are they? We pay them (60% of 1% of some percentage of all bets) but in return they give us nothing.
A similar idea was suggested in the JD chat some months ago, I think by uvw, but maybe by somebody else. He proposed having 3 tiers of investors, the regular ones we have now, the "coward" tier (like the ones you propose) and the "hero" tier, who take the 40% 'risk cut' that the cowards don't get, but also pay the cowards when the house loses. This idea fails for the same reason - the 'cowards' are effectively parasitical at the expense of the 'heroes'. They get a guaranteed return on their investment, but we're not free to use their investment for anything because we've promised never to lose it.