It can be a good business if you have a few rooms. There's two types of people who get into it: passionate people, and people who buy designs online for a decent revenue. The latter makes more money, but there's some amazing escape rooms that are Disney-parks-level.
Unfortunately, escape rooms work way better in non-cities. Rent is too expensive in big cities, so the rooms suffer. Many of the best rooms are in really random places, since financially it works out better. It's a really interesting space, and I'm starting to see a few big companies form around it. I am curious to see if big companies (with decent but generic games) overtake the smaller passion project ones.
(Money aside, designing and building an escape room is one of the most fun things I've ever done. There was a solid mix of cool tech, puzzle design, prop design, showmanship and more. If you're interested, I can help get started! My email is in my profile)