>confined to the house. Her energy levels are through the roof. Yes, SOME cats can be happy spending their whole lives indoors (although I do believe for most of them the quality of their lives are significantly less), but she can't. You've not had to deal with her. You think you could train her, but you couldn't. Not all cats are the same.
5. I didn't have a cat for 20 years because I didn't live somewhere it would have been safe to let them out. Now I do.

What applies to you is not universal.