Do owners of betting companies place bet on their own platform or is there a policy specific policy that restricts them from betting. Do you think that there would be conflict of interest or that it will be unethical if owners bet on their own platforms. These are the questions that I am seeking an answer to.
I don't think most of the sites have any terms that forbids the owner from placing a bet and in most of the cases it don't even matter.
Many of the games and sports betting results would be unknown for the owner themselves. So, they are equal to normal players there.
The cases in which the owner knows the outcome beforehand, there still won't be a problem if the site provides the entire bankroll on its own as the owner would be gambling against himself.
On the rare case of owner being able to see the outcome beforehand and users have ability to provide the bankroll, there's nothing that could prevent the owner from cheating the bankroll investors. Anyone providing the bankroll should have complete faith on the moral responsibility of the owner.