2 minutes later, I set my time machine to go 1 minute back in time, collect the coin from myself, bring it to the present. Now I have 2 gold coins.
I don’t follow. If you took the coin from the past, it no longer exists in the present. You still have 1 coin. You are duplicated, however, and now two of you exist in the present timeline. You could do the duplication glitch by taking the present timeline coin back to the past and giving it to past self, who now has two coins.
Ever shined a powerful flashlight or laser around and seen all the particles floating in the air? You can also see them sometimes with a particularly bright sun beam coming through a blind. While these visible particles probably aren’t spores, it does illustrate how much stuff you’re constantly breathing in. There is no escaping. You’re part of life, there’s billions of organisms on you and in you at all times, and they’re fighting for survival too. There’s no escape. The only reason you survive is because of your immune system, and that’s why immunodeficient people like severe burn victims and AIDS patients just die despite nothing particularly “wrong” happening to them.