Do you think that the owners of casinos and sports betting platform, gamble as much as other people do? If they gamble, do you think they gamble on their platform?
Business owners will not jump into a venture that they don't know themselves.
Same as casino owners. They will not jump into something that they don't know and knowing gambling is very addictive (to some), I believe that they gamble as much or even more as normal gamblers do.
Where are they gambling? I believe it's not on the casino or website that they own, but on other casinos or websites. Maybe they are doing this so they can see what are the features these casino or websites has and they might implement it into their own platform. I've also seen small gamblers here in our place who are also gambling, but on a different platform and not on their own platform.
Eddie the founder of Stake.com which you are promoting is the best example on casino owner that gambling on their own casino. He created promotion which is Stake vs Eddie that players on Stake needs to beat his multiplier in able to win. He is known for doing live stream of his game.
I believe other casino owner play on there own casino discreetly because they will not enter on this business if they are not into gambling by themselves.