This logic could also be used to argue that acetaminophen / ibuprofen should be Schedule I narcotics since taking a dose 30x - 50x larger than the therapeutic dose would almost certainly result in death.
I disagree with your comparison of acetaminophen and amphetamines. It seems to be based on your deluded idea about dosage, but other than that, the drugs differ in some rather significant ways such as abuse potential, habituation, psychoactivity, and so forth.
You can disagree with my comparison if you'd like, but the fact remains. Don't take my word for it - I encourage you to read some of the research out there surrounding therapeutic methamphetamine as well as the more common levo/detroamphetamine.
Amphetamines are highly addictive. They require perpetually higher doses to maintain the same activity in the body, like most other highly addictive substances. I'm sure there are some legitimate therapeutic usages for these drugs (narcolepsy). However, I see them as massively over prescribed to people who do not actually require them.