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.