If those 5 have gotten enough people to come, most of their patrons will happily come do yours, too. You're not really "competing". In a way, you're more like a movie than a movie theater.
Could escape rooms go on tour like theatrical productions? Producers swap escape room teams/spaces between cities? Professional roadies who are expert in setup/teardown?
There's also many companies that sell escape room plans. So rather than creating your own, you'd spend $5-10k to "buy" one and then build it yourself. They usually guarantee a X-mile radius that you'll be unique, so that you aren't competing against the same game.
The escape room in my town reconfigures every once in a while, I've done about 5 different "rooms" there that have all been very different. Sometimes the theme requires you to know something about the topic to solve the room (examples: star wars room, comic book room). To be honest they probably rotate the rooms.
Books are completely indefensible. There are billions of the things, and new ones get written all the time. I made some money. I was and am very happy to have written books.
Is writing books a good business? Perhaps not, if viewed through the “The world is divided into unicorns and NOOPs” lens. But I don’t look at the world through that lens.
See also: Making music, opening a social pub, running a day care, organizing festivals or conferences...
Also, if there are more than about 13 in your market, you’re going to have problems getting noticed because the review sites have huge first mover bias.
In general, the market is over saturated, and will probably see more closures than openings over the next year.
How’s the best way to measure if the market is saturated?