As I explained in this very thread the roulette could easily be very unfair and the current hashing scheme would do (literally) nothing about it. Since the next numbers are generated on their server, they could easily say - "in the next 16 rolls it will always return 16". And you still get the hash before the roll, roll happens and after the roll you can confirm that indeed 16 was rolled. If the insider bets on 16, then they can nicely multiply a lot of coins (while other people betting are most likely to lose). Obviously they could make the roulette less visibly unfair, so it goes unnoticed for longer.