Since online businesses don't declare their revenue publicly, it's difficult to tell, but from a general point of view and an understanding of how different platforms and services work and how they earn money, I believe exchanges and casinos will be the top two businesses with most revenue among online businesses. We might think that casinos earn a lot of money, but we can't ignore the fact that centralized exchanges earn a hefty amount as well since they provide a lot of services and they earn money on each service they provide.

I think if a casino and a centralized exchange have the same level of user base, they might earn about the same because if a casino earns money from house edge, an exchange earns from trading fees, if a casino gets money when a player loses, an exchange earns as well when a trader gets liquidated, and if a casino has to pay the winners, an exchange has to pay those who earn profit on futures trading.