> And there's very little evidence it's any more addictive or harmful than normal amphetamines.

Well, I won't say "just try and compare" because recommending to try that would be a devil's advice but the difference is huge and I don't need any scientific paper to confirm that. For a person having actual ADHD amphetamine can be a reasonable tool to manage it sustainably, at the same time meth would at least cause rapid tolerance build-up leading them to increase dosage very fast and face all sorts of health issues. You also won't be able to return to amphetamine soon after having tried meth, the former is going to have almost no effect until your brain chemistry actually recovers.