That what I’ve told all my girlfriends. They’ve all said I have beautiful eyelashes and they want to know if I do anything to them.

I have literally never touched an eyelash besides wiping one out of my eye.

When I had shoulder length hair, I washed it with head and shoulders every other day and never got split ends.

Now some of that is probably genetics, but also I do think that so many beauty products that women are sold is designed to keep them buying shit to “fix” things that their body will eventually fix on its own. Humans didn’t evolve washing their hair with 3 different soaps every day. Hair just kind of takes care of itself, and the only thing that might need fixing is dandruff.

That sounds like a myth. I had a friend who lost his hair in his early 20es. People told him it's because he was wearing hats most of the time. Another friend lost his hair at the same time and was never wearing a hat. I still have most of my hair at 40 and i wear a lot of hats and always have.

Like a rubber hat? I also doubt that the hair itself "needs oxygen" so much that a tissu will prevent the dead thing to like look ok?

I'd say genes and too much cleaning away fats and stuff from the scalp.