I can't think of anything more profitable at the moment. Although I don't know in depth the income from online casinos.
However, to create an online casino, you need a lot of investment and be willing to pay for advertising and interact in a forum like this.
I don't intend to have an online casino, I'm more interested in having an e-commerce.
One of the factors that makes me believe this is that there is already a whole audience ready to play in casinos, as they are generally people who bet out of addiction, to make money (or even when they lose, they play just to pass the time). In addition to the fact that there are costs for servers, employees, online attendants, programmers and other costs, unlike physical casinos where the costs are for installations, maintenance, energy and employees and security guards...
Do they make more profit than digital banks, CEX exchanges, etc.?
Maybe compared to the bank, yes, the casino is more profitable because there are more gamblers and large deposits. The income is also high, especially if the players in the casino are rich. But compared to the CEX platform, I don't think the gambling casino online is more profitable.
Because there are more people who invest in cryptocurrencies or bitcoins compared to gambling, it's just another thing that people think gambling is good; there are more opportunities in exchange compared to gambling. That's the truth.