dude, I did adderall -> meth every day for 10+ years and I am one of the sanest people I know. I knew one other guy who had his shit together as much as me and did as much as me. Everyone other tweaker I knew were fucking idiots.

I think it had to do with the slow steady pace that I raised my dose. I started with prescribed adderall, then very small amounts of meth when i ran out early, then just straight meth because i got sick of going to the doctor every month. And very slowly went up and up and up till i was bangin .25 every 4 hours. Even then I was still relatively sane. I knew hallucinations for what they were, and held down a good paying programming job through all that.

I took a lot of dmt and acid in those times too. Which I think had a lot to do with keeping me sane. Psychedelics form new neural connections.. or perhaps just reformed the ones I had lost.

Also lots of people who take meth start out pretty fucking stupid in the first place, and also a lot have preexisting mental conditions. So god knows it cant be good for them.