DISCLAIMER: My own startup, Buzzshot (
https://buzzshot.co), makes an Escape Room software SaaS product. I've been running it for 2 years and its been my full time gig for about 6 months
The article doesn't talk about it much but there's also a booming support industry that's built up around Escape Rooms. From prop makers, puzzle desingers, suppliers of full turn key rooms.
It's a fascinating industry to work in. Having spoken to every customer on the phone (highly recommended) there's such a range of people starting Escape Rooms from people starting their first ever business to people with lots of experience in related (or less related) areas. The amount of different skills that go into making these things is amazing. Having multiple rooms seems important to growing revenue, since it's the only practical way to get return customers. A lot of people of expanding to multiple locations as well as a way of reusing work.
A cool thing happening right now in the UK is two rooms are openning using licensed IP. There's a Dr Who one which sounds really exciting and one based on the Benedict Cumberbatch Sherlock show (disclaimer no 2, they're a customer of mine which I'm very excited about)
They're a whole lot of fun to play as well :)