The laundromats around here closed down years ago. Not a characteristic of extremely profitable businesses.

There are a couple of strip malls nearby that have vacant rentables, vacant for years and years. Nobody has thought to put an extremely profitable laundromat in any of them.

This is anecdotal - look this up outside of your strip malls. It has the some of the lowest failure rates of just about any business and 20-35% ROI

I've heard that laundromats are used for money laundering. This may explain their profitability, but it's a front, not a business.