The 1% max bet doesn't really stop everything because you could just split the bet into 2, and now you have a 2% max bet. Someone could cleat the full 26k site bankroll with about 3Mil by just always betting at 98% until the site is bankrupt.
I don't understand what you mean.
If you can bet 100 btc in 1 bet, you have 49.5% chance to win 100 btc. It is likely to happen.
If it is capped with 1 btc max. You make 100 bets worth 1 btc. You now have 1.429E-31 % chance to win 100 btc. It is impossible to happen.
The expected value is the same, but the variance isn't.
It should not be possible to bet more than 1 btc/bet. If someone wants to bet > 1 btc, the website should split the bet into xxx bets.