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.?

Q: How much money does an online casino earn?

There are tons of casinos that are publicly trading, so their earnings are available to the public. For an example, you can Google Betsson AB Quarter Report, and you'll see that they are ranging around 50 Million per quarter, but they are also a huge operation that eats a lot of money by itself. Smaller operations usually earn anywhere between 250.000 to a million per month, but since it's such a volatile market, you have to have a fat war chest for hard times.