The point I’m making is that when people frame this as “some people just aren’t built to handle it” they put people into two groups: the easily addicted, and normal people.

What makes you think I am doing that? All I was trying to say is that something serious must be happening for someone to get addicted from trying low dose amphetamine once. Suggesting that's a common outcome is the most DARE shit I have ever fucking seen.

I think that’s an incredibly dangerous framing of addiction. Everyone is capable of becoming an addict. Just because some never do, doesn’t mean they had some special mutation that protected them. Addiction is an incredibly social disease, and with how little we know about it we should be more cautious rather than callous when discussing it.

You're aiming this at the wrong person. I am not the one suggesting here that addiction is purely down to genetics. Addiction comes down to a lot of different situational and psychological risk factors. Poverty being a big one, as well as stress, depression, anxiety, and so on. You don't need any genetic predisposition to become an addict, I agree with you there.