Do you feel this way about all mind-altering substances, or is it a function of ubiquity?
Where do you draw the line? I actually agree with you in theory: I think most people should try most things. I think my line, though, is a function of potential for addiction and abuse. On that scale, though, alcohol looks as bad as amphetamines, and far worse than something like MDMA.
If ubiquity is your primary factor, do you feel the same way about cigarettes? Should everyone try them to see what the fuss is about?
There's also this societal concept that everyone has vices. And people would rather be able to recognize and see your vice, rather than have it be unknown. Bill Cosby comes to mind.