Neurotransmitters fire/misfire/go-on-strike etc........ and work differently in people.
Sounds so obvious, but just had to start there, let's move on,
Maybe this helps, maybe not.
For me, Ritalin prescribed for ADHD , always had plenty left over when new script should be requested (IR release too), kinda felt like "better than nothing", but still was "self medicating" and no alternative available at that time and never thought there was another way.
Before that in the "hey days".. when cocaine
came to visit, it almost had no lasting effect, if any, gone as soon as it arrived ... just not worth it for me.
Even back in the day people looked at me as if I was crazy, when I declined lines of coke. - it was just numbing, got a little rush of warmth for a few minutes then blocked nose and fluey for the rest of the time thinking the more I have the better I would feel, dropped that idea quickly.
The research and reading I did actually made sense regarding those two chemicals for purpose, just not for my purpose.
However, Amphetamines, the longer lasting, smoother, cleaner feel, was my "social" escape and known poison (yup, guilt), So conned myself that no re-dosing like a lunatic etc. and yeah, I could control it.(back then it was crystal orally

not proud of it but no regrets on lessons learned). And no, it controlled me, but I tried my best and trusted my gut and guilt.
Been a good boy for 9 years now.
The missing piece of the puzzle was found 3 years ago, Vyvanse. One a day.
Wires are connected now, no guilt, no doubt and no more searching.
Weird huh?
Hope this helps.