Today almost all gambling sites feature Provably Fair system for their games. If you are not familiar with it, it is based on cryptographic hashes - the result of each bet is based on 2 seeds, one of each comes from the player side and the other from the house side. This system is used to verify that every bet was truly random without any manipulation from both sides.
The problem here is there's a third side involved in gambling - investors. They invest their money into casinos bankroll and share profit when players lose, or cover house's loses when players win. Now my concern is that investors don't have any control over seeds, so there's a potential for abuse by casino operators. They could simply create player account and make fake winnings, since they know both seeds, and by doing this they will be stealing investor funds without any way to prove it. Of course investors will start withdrawing their money if they will see losses over long term, but this scam could be even more subtle, for example living investors with profit, just smaller than they should have earned so there wouldn't be any suspicions. Considering all this, I think gambling sites should extend Provably Fair system to cover investor side.
Your concern is right and even a source of concern to every investors engaging in bankrolling. But as you rightly noted an investors coming in with his money knows that there is a risk of losing his money at the same time the player coming to wager his own money is also aware of the same risk. So they are all in the same shoe and should be happy about and I think the provably fair system is good for both parties that will be happy that even if I lose my money either as a gambler or investor, what matters is I lost fairly...