We may be seeing a pronounced barbell distribution in the profitability of gyms:

One way to see it is to look at the two gym brands commonly cited as the fastest-growing in America: CrossFit and Planet Fitness. Both are expanding like crazy. CrossFit has gone from having 13 affiliate gyms in 2005 to 10,000 today. And Planet Fitness has more than tripled in size over the past five years.

But aside from their bang-up growth rates, the two could not be more different. The former is expensive and intense, appealing to competitive individuals ready to commit thousands of dollars and many hours to working out. I go to a CrossFit gym a few blocks from my apartment. It costs $160 a month, often more than I spend on groceries. The latter is perhaps most famous for giving out free pizza — a fact it embraces and publicizes, no less. Its monthly fees are normally around what a movie ticket costs.

...

It is the middle that is growing more slowly, with some chains struggling to demonstrate their value to consumers — your Bally Total Fitness, now all but defunct, or Curves. It is the gyms with considerable but not intolerable monthly fees and decent amenities, but no sheen of luxury or promise of extraordinary results.

Or perhaps this is some variant of the smiling curve, with high end gyms offering the value add of the company of the other well-heeled folks embracing a high cost public signal of their willingness to spend on their physical fitness (itself a signal of many other things, including self-discipline, health, and matching level of vanity).