> I'm persuaded by my personal experience as well as testimony from /r/keto

Being healthy and athletic in the short-term is one thing, living a long and happy life is another. I always feel that the Paleo/low-carb communities focus on the former, but if you can believe the gist of The Blue Zones, then happy centenarians have very "boring" eating habits (statistically speaking): https://en.wikipedia.org/wiki/Blue_Zone