They look (to me) like they just make that effect where some people get hung up on certain classes of ideas way stronger, if it happens to be video games you won’t get anything done but if it happens to be math then you’ll probably get very good grades.
The problem with using them as an adult is that success as an adult has more to do with effective socializing and less to do with ability. People high on these things are the worst to be around. There was one guy I thought I hated the whole time I was in college and he got off this stuff and it turned out he was an awesome person sober! Most of the other people I know who were on the drugs are similar.
I’m not saying amphetamines are bad but there not magic either. Personally I think the psychoactive effects of chocolate and coffee are plenty for most people and it’s all about managing it.