I would caution that just because your body can make something doesn't mean it will have optimal performance when doing so. People in ketosis do have worse peak performance in sports than those that eat more carbs/sugar.
Or do I want to live longer?
They aren't necessarily mutually exclusive, but different actions could result in different outcomes for each.
For nearly everyone, this isn't impactful to their life. Only their vanity
I'm not saying that ketosis has this kind of an effect, but rather that eating or not eating some other things might. Eg vitamin K2. The body is be able to make vitamin K2, but we might have stronger bones and teeth, and a healthier cardiovascular system, if we get extra K2 from an external source.