Been trying to figure out the closest thing arcane addiction is like, because we have no such thing as "arcane" source or energy that a race can use to do magic.
Arcane
I believe humans can get addicted, although it doesn't seem as much of an issue as it was for the elves.. unless the elves are grossly exaggerating things because their standards are much higher. So what may seem like addiction to an elf is not as you or I would imagine nor what hte humans would cause.
Fel is more like drugs in my opinion with the exception that it actualy gives you power.
Arcane is actually the building blocks of universe, andd we know it extends life, intelligence, health, you also grow bigger -- it's more like food and sugar.
Also it appears that elves have a naturally higher capacity for it.. so the level of magic usage that might get other races addicted or crazy won't do so for elves, night elves would have a naturally larger capacity than Thalassian elves who devolved slightly after the exile - besides the WEll of eternity is bigger juice than the Sunwell/
If elves use magic in crazy amounts they would naturally get addicted, the night elves of Suramar went the further, ingesting mana for food, which caused the whole withering problem, and is likely the reason their appearance shifted tot he skinnier nightborne version of night elf.
It would also appear that Thalassian elves likely did not realise they would get addicted by merely being suffused by the sunwell. Best theory I've heard is because the exile, the high elves devolved body cannot handle the same amounts a night elf would, but they probably didn't realise they were at risk of addiction through suffusion - or maybe they did, but didn't think it possible - the story shows them as haters of the addiction and reckless attitude of their former highborne night elven roots, and wanted a society free to study arcane unlike the long vigil group, and definitely anti-demon, anti-recklessness and addiction unlike the pre-sundering highborne led kaldorei empire.
Night elves post sundering are not addicted despite being suffused with the more powerful well of eternity, this is discovered to be because they live balanced with nature - 7.0 reveals that balance of nature prevents arcane addiction for a night elf, in fact teh arcan'dor addiction cure, utilises a balance between arcane adn nature to cure the chronic addiction of the nightborne.
It appears this is not sufficient for a high elf, hence a fusion of the holy energies with the arcane in the sunwell is the only thing that keeps them balanced, meanwhile all a night elf need do is eat a fruit or abstain for a few years and is recovered.
As far as I can recall, the high elves who never used or were exposed to fel weren't cured from their addiction in a few years, in fact, not until the sunwell was restored .
Fel
Fel is far more highly addictive, and it corrupts/distorts the body, lesions/scars, rotted flesh are the marks it bears and it is quite destructive to you and those around you.. in this it is much more similar to Class A drugs, with needle and track marks all over your body. It distorts your mind and your body..
Demon hunters show remarkable capability with the addictive nature of fel - I presume that the struggle against the inner demon is an even tougher one and their sheer will and determination is what affords them to be victors and not victors of fel lust/addiction.
The arcane runes seem to help with both the demon within and the corrosive/corruptive and maybe even addictive aspects of fel.
Those who use fel are normally quickly consumed by it.
Fel seems powered by draining life in a highly concentrated form that causes the victim to shrivel up and die - (see Warcraft movie), and their soul energy furhter empowering it.
I suspect once you go fel you don't go back.
i also suspect fel and shadow have a connection or cross over.
I think only demons and demon hunters seem to have high capability with fel. Warlocks seem a lot more limited in their fel usage, possibly because those who use it become distorted by it.. like gul'dan demons, etc and the warlock is not distorted, besides blizzard only allowed fel green glyph, so normal Locks can't really use fel magic outside the one destruction bolt and mixing traces of it with shadow.