Casual spin rider

So there is a woman who attends at least the Tuesday night spin class at my gym. I can’t quite remember if she comes on Thursdays.
Anyway, she just leisurely rides her bike. And really I am no one to judge anyone in spin. Everyone needs to go at their own pace. But why waste time at the gym when you don’t break a sweat? And I can’t possibly see what she gets out of it.
She would be better off taking a ride outside with a view of something more than someone’s butt.