I have had cats for years (all indoors). I used to be a vet tech, so definitely see the benefits of keeping them indoors.
I have one left now, who is partially deaf and 16 years young, she still climbs up her 6 foot cat tree. Amazingly, she survived the big move last year from CA to NV, and our younger cat stressed out, got sick, and had to be put down. Most of my cats have been pound babies.
Waiting to see if we end up with our son's cat, he's in the Navy and based in Spain, but is probably going to switch to Army and will have no room for her. So he will either find her a new home there, or ship her to us. She's only two or three (also a pound baby).
I did have several dogs growing up. A pound baby, a German Shepherd, and a Min Schnauzer, all at different times. I love cats and dogs.