Mainstream gyms are attracting normies. Normies who come with casual goals and for a sanitised experience. They want people who come sometimes and then carry on paying but never really use facilities. Half the people in normal gyms have never actually done any reading into how yo do exercise or what they're training or how to avoid injury. Even the treadmill runners don't have a plan.... They just run till they're a bit tired and sweaty.
Weights gyms are different. Muscle heads intimidate normies. I used to seek out weights gyms and they would mostly be dark, dingy places. "Rough" looking places with "rough" looking people. Many have attached UFC or boxing training. People tend to come in groups and spot each other. There's grunting and weights banging. You may need to wipe someone else's sweat off a bench. The music may be non-mainstream. It's scary for the uninitiated.
