I think you're anthropomorphizing housecats a bit here. A housecat who gets multiple square meals of catfood a day, played with, gets to cuddle with their owner or other cats, and sleeps safely in the sun for 3/4 of the day will live a happier and longer [1] life than an outdoor cat.

Now, you have to still mind your indoor cat. They need stimulation (look up "eat hunt bathe sleep") and attention and a good diet and cat-friendly environment. But give them that, and there's really no argument that being outdoors is obviously better. It's more that the outdoors gives some of that stuff by default, so compared to a cat owner who doesn't fully invest in their cat, maybe there's a case.

But if you understand cats, you get that that "coming alive" isn't some "free at last" sort of thing.

[1] Outdoor cats die way earlier than indoor cats