That Provably fair stuff is about the randomness of rolls. Not about the owner or about what the casino doing with it's own coins. So that covers many trust issues indeed, but not all issues/possible issues.
But if a casino gambles with investors coins, the long term probability is to lose them... am I right?
No, he think that if owner play on his own (provably fair) dice site his clients have less chance to win. This is like theory - if someone play more have more chance to win..