A little trick for technical articles that I've found is to use screen readers.
On my phone I've read 250k word books cover to cover, same books I could never read on a PC. Attention is weird like that.
Another trick is getting your dopamine* externally. There's an association between ADHD and substance abuse, and I can see why. Pharmacology is a cheat code: a few hours of infinite motivation, will power, and attention.
Unfortunately, when people start needing a substance just to feel normal, that is the definition of an addiction.
(* More complicated than just Dopamine or Serotonin, both seem to play a role. Medecine has not solved this one yet.)
If they would otherwise not feel normal and there are no negative side effects, is that a problem?
Negative side effects of note with usual ADHD medication (amphetamine salts) include increased cardiovascular load, development of a tolerance (you need higher doses to achieve the same effect). Sometimes amphetamines induce small changes in personality, rarely full blown psychosis (this has happened at therapeutic doses!).
In general you should apply the same sort of risk-benefit analysis we use for every other drug. If you don't experience any side effects so strong you want to stop, and you believe you're aware of the risks, great.
If you're taking them without a script, I'd advise you to find a steady-state dose that works for you and stick to it. Don't let yourself increase the frequency or the dose without a conscious decision. That's how many people have spiraled.
Finally, I think it's important to have a lot of respect for psychoactive chemicals. Nature doesn't care very much for human overconfidence. If you start being careless, chemistry will do what chemistry does.
I'm a prescription-attention-drugs person and specified drugs do not exist.
Disagree. What is 'normal'?
A better definition for addiction is the brain no longer produces the neurotransmitter without the presence of the drug (or is doing so at a highly diminished rate). There's no evidence that such occurs with the amounts prescribed for adhd.
For that matter, people needing an external source of a substance to feel normal is unavoidably part of being an organism. We need water, or we wont feel normal. We need vitamins -- and plenty of people have vitamin deficiencies, are they addicted to said vitamins?