This isn't true, studies has shown that taking stimulants has no effects on grades for normal people. The "increased focus" they experience is just perception and not fact, it can even hurt their ability to focus. Being able to sit with a task for hours isn't "focus".
https://www.webmd.com/add-adhd/news/20180726/adhd-meds-no-he...
> The students also showed an improvement in their alertness and their ability to focus, the researchers found.
The idea that only ADHD people see improved focus from stimulants is purely false, as indicated by the article you provided. It's a dangerous misconception, as many people use this misunderstanding to self-diagnose as ADHD when they take their friends' stimulant medication and experience improved focus. We need to be clear that non-ADHD patients still feel increased focus from stimulants as well.
You are correct that over-medicating with stimulant medications can harm certain types of cognitive function, in both ADHD and non-ADHD people. Dopamine has a well-known inverted U shaped response curve for certain cognitive processes. Going too far past the optimal point can worsen, not increase the focus changes.
The study also used a strangely high dose of Adderall. 30mg of instant release Adderall (equivalent to 60mg of Adderall XR) is actually beyond the recommend prescribing guidelines for ADHD. That's the type of dose that would typically only be prescribed to patients with severe narcolepsy or severe, intractable ADHD. I'm not sure why they thought it was a good idea to give it to medication-naive study subjects.
Also I'm not sure what your point is. Yes many people abuse stimulants in this manner and hurt their life due to it. However many people also greatly improve their life using stimulants. The existence of the first group doesn't mean much for how I need to use the medication, all I need to know is that the medication greatly improved all aspects of my life going from an almost certain failure to a top performer. If you don't see life changing improvements in grades or job performance then you probably don't have ADHD, at least not the same kind I have.
Most people will experience increased focus when first taking stimulants, ADHD or not. Many ADHD patients will experience euphoria with their first doses. The idea that ADHD people have polar opposite responses to medication is largely a myth.
Most long-term patients don’t identify with the euphoric or energizing comments because they’ve built a tolerance to those effects. There’s nothing wrong with that, because the therapeutic value doesn’t derive from inducing euphoria.
However, a drug-naive college student taking a double dose of Adderall will certainly be buzzing. For a short while. They will then suffer a rebound on the following day or days. There isn’t really a free lunch here.
The challenge is that non-ADHD people often try Adderall once, like the effects, and assume a positive response means they have ADHD. That’s blatantly wrong, but it has lead to many people pursuing unnecessary stimulant prescriptions in hopes of feeling that way every day. They are always disappointed when they discover that the long-term effects are very different than those first experience effects.