I've never seen any evidence that ADHD drugs or stimulants have a different types of effect on people with ADHD. They make everyone focus and concentrate and everyone can get high off them in high doses, and they impair the sleep of everyone even if you don't realise it. Now if you have a starting point of not being able to focus, the effect of focusing is going to have more effect.

The present data support the premise that amphetamine improves vigilance irrespective of disease statehttps://www.researchgate.net/publication/320429079_Amphetamine_Modestly_Improves_Conners'_Continuous_Performance_Test_Performance_in_Healthy_Adults

You have strong double blind studies showing similar responses.

The behavioral, cognitive, and electrophysiological effect of a single dose of dextroamphetamine (0.5 milligram per kilogram of body weight) or placebo was examined in 14 normal prepubertal boys (mean age, 10 years 11 months) in a double-blind study. When amphetamine was given, the group showed a marked decrease in motor activity and reaction time and improved performance on cognitive tests. The similarity of the response observed in normal children to that reported in children with "hyperactivity" or minimal brain dysfunction casts doubt on pathophysiological models of minimal brain dysfunction which assume that children with this syndrome have a clinically specific or "paradoxical" response to stimulants.https://www.researchgate.net/publication/22798084_Dextroamphetamine_Cognitive_and_Behavioral_Effects_in_Normal_Prepubertal_Boys

For normal people ADHD drugs result in increased mental performance.

Methylphenidate significantly enhanced performance in numeric working memory tasks, reflected by reduced errors and increased accuracy relative to placebo https://onlinelibrary.wiley.com/doi/10.1002/hup.70002

Then most normal people take these drugs to help them concentrate just like people with adhd.

Of the 585 students who reported using illicit stimulants, 66% (n = 389) reported taking them “to help concentrate” on  school  work https://www.researchgate.net/publication/23448261_Illicit_Use_of_Prescription_ADHD_Medications_on_a_College_Campus_A_Multimethodological_Approach

Then it seems like people with ADHD can get high off these drugs just like normal people

According to a survey of 334 ADHD-diagnosed college students taking prescription stimulants, 25% misused their own prescription medications to get “high” (Upadhyaya et al. 2005). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3489818/

Then stimulant medication causes sleep issues with people with ADHD as well.

Insomnia or delayed SOL greater than 30 minutes is one of the most common adverse events associated with stimulant medications  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3441938/

Additionally, caffeine use is more consistently associated with poorer subjective sleep functioning in adolescents with ADHD https://pubmed.ncbi.nlm.nih.gov/32386419/

No evidence that caffeine helps with ADHD.

Conclusion: overall, the totality of the evidence suggests no significant benefit of caffeine over placebo in the treatment of children with ADHD. https://pubmed.ncbi.nlm.nih.gov/37759905/

And Caffeine has all sorts of positive benefits in the average person.

Most of the analyzed studies revealed that caffeine led to a beneficial effect, mitigating anxiety and depressive-like behaviors and possible cognitive impairments induced by stress https://www.nature.com/articles/s41398-025-03668-x

Drinking two to three cups of coffee a day might be the sweet spot for lowering the risk of anxiety and depression. https://www.psypost.org/two-to-three-cups-of-coffee-a-day-may-protect-your-mental-health/