Reasons ...

... why people shouldn't go to the gym. 
2. For attractive decor, fancy equipment, or an expansive range of equipment. It's not about that. It's about showing up regularly. 


... why people should go to the gym. 
2. To show up regularly and get regular exercise, however strenuous. See #2 above. If you pay for the extras, but still don't show up, you shouldn't join a gym. 


Comments ...

.... about why people should or shouldn't go to the gym. 
1. Yes exercise burns calories. But it can also make you eat more. www.fitnessmagazine.com/weight-loss/eating-help/control-cravings/control-your-post-workout-appetite/ Your weight depends 90% on how much you eat and what foods you eat. If you can't control your diet by eating less, exercise is not going to be a magic solution. 
2. Sure, if you need to swim, look for a decent pool. But for the most part, if there's an old exercise bike, without any bells and whistles, and a couple of safe machines, and if you show up on a regular schedule, you are getting 75% of what a gym is good for. Plus a basic gym is more likely to be less costly. If fancy or even extravagant is absolutely necessary to get you to show up ... go for it.