Here is my input as a high stakes gambler:
All of these casinos have departments or people specifically monitoring winning accounts (withdrawals etc)
If the account wins too much, they can limit their stakes. (Happened to me. Highly unethical.)
Another thing to consider, there is absolutely nothing stopping the casino from giving you bad seeds or adjusting your win percentage algorithm to stop you winning.
A casino is a business, if you take their money they eventually have to close. Although this should be offset by 99% of losing accounts.
However some casino's are so greedy that they won't even allow the 1% to win... (prime dice)
Essentially, casino's are nice as long as you keep giving them money. But if they start to lose more often than not you are an immediate problem - and it's no longer "fair".
My worst experience has been with primedice, where my account was destroyed with limits and then set to lose.