There's an easy experiment OP can do: see if nicotine patches help.
Nicotine is a safe stimulant that available over the counter; and works really well against ADHD and can help normal people too. Arguably much better than caffeine for the vast majority of people.
As someone who just quit nicotine (e-cigs/NRT/tobacco-free “dip”) after nearly a decade, stay away from it at all costs. Nicotine is a wonderful brain stimulant (nootropic), but it’s far too easy to become and stay addicted.
Interesting. I only ever tried the patches on and off, and never had any problem stopping. The research that Gwern collected at https://www.gwern.net/Nicotine seems similar.
I never smoked or tried e-cigarettes, though. Smoking is awfully addictive.
I tried half a nicotine gum once. But the stimulant hit was too much at once and made me nauseous for about half an hour. (Similar to eg the effects of way too much espresso, but with much shorter duration.)
Did you ever smoke burnt tobacco?
What was the process of quitting e-cigarettes (and the others you mention) like?
Nicotine is a safe stimulant that available over the counter; and works really well against ADHD and can help normal people too. Arguably much better than caffeine for the vast majority of people.
See https://www.gwern.net/Nicotine for details.
One thing to keep in mind: stay away from smoking. That's vile and addictive.