If you can't provide sufficient enrichment to a pet that you own and made a personal commitment to care for, rethink your decision to have a pet. My dog would go crazy in the house too if I spent as little time interacting with her as most outdoor cat owners seem to spend from comments like yours. You can also take your cat out on supervised outings like people do with dogs.

Studies show that indoor cats not only live longer, they have lower amounts of stress related hormones in their blood, suggesting that they are less stressed/scared or don't get stressed/scared as often. You can subjectively claim that your cat is miserable when inside and you're probably right about your cat and its specific personality, but the data shows that the majority of indoor cats are doing fine provided they have an owner that doesn't ignore them.

Also, you know where outdoor cats take their shits so your house doesn't smell like cat turds? Other people's yards and gardens. I pick up my dog's shit like a pet owner should and you're proud of the fact that you just let your cat shit wherever it wants?