Research has found those who use medications such as Ritalin without having conditions such as ADHD actually reduce their mental performance on cognitive tasks.
The interesting point was that the meds did sometimes did have an effect, but often it was more about focusing energy in the wrong direction.
As someone diagnosed with ADHD, I consider myself actually really good at focusing, when I am on good enough mood and I am interested in the thing I am focusing on.
But thing is, most things don’t really interest me. Like work, house chores, etc. And I just can’t get those done. So with meds I am able to focus on those things and get them done well enough, but my performance and quality of work is never on par with the way I organically focus on things.
In an optimal world I don’t think I would need meds to get by despite my ADHD, but modern life is so busy and hectic. I think that is what drives people who are not ADHD to take these stimulants to boost their productivity. People are not pulling all nighters with modafinil and adderall just to have a good time.