Indeed, with many risky investors
the max profit increases uncontrollably (think something like 1000 BTC) and hardly anyone will ever challenge that;
That's not a safe conclusion to make.
Remember there's big-odds gambles available - the max being 990000:1.
So someone only has to bet .00101 BTC on that bet to hit the max winning cap.
At present there's about 15k BTC invested. If everyone in there went with 100% risk exposure (so max winnings 15k BTC) a single very lucky .01515151 bet could clean the whole bank.
Don't confuse a 1000 winnings cap with somehow meaning gamblers have to risk 1000 BTC to put it at risk.
I wouldn't be at all surprised if a nsignificant number of investors regularly bet their small investment gains on high-odds bets. If they lose their capital is still untouched and if they win they get some nice winnings. If someone leaves 10 BTC there and gets 0.1 BTC interest are they going to take out 0.1 BTC or have 100 'free' spins at trying to win 1k BTC? I reckon quite a few will do the latter.
If the number is truly random, which I believe it is, then the house can't lose.