Wagering at your own casino isn't going to make you rich either

that's why most of them have a clause that says you can't be a casino employee to register on the site. The sites that do have employee accounts (mostly smaller casinos that don't have an army of devs to make a management panel), don't play any of the games.
Gambling is an addiction. For those who are losing huge amounts of money, it's not fun for them. When you have your own casino you are basically losing your own money. But the benefit is you are having the fun part and covering the addiction part too.
I do not think the addicted gamblers gamble for money but the habit is what they chase. I know or even used to be a guys who used to lose a lot everyday but the day I win a log I giveaway a good percent as tip. End of the week I was losing from my own. It's very similar story for all gamblers.