Hardcore gym rats need the special equipment found only in gyms. For example, the squat rack. You can't find this in a typical Sinkie fitness corner.
The treadmill is a good alternative if you don't want to do cardio outdoors, for whatever reason.
Of course, you also have the vain bicep-kissing chaps and the itchy CBs who use the gym as a habitat for selfies, socializing and 'networking'.