To expand on that, I think it can be clarified somewhat by describing the mechanism at work. People without ADHD have a generally-working motivation/reward sys

To expand on that, I think it can be clarified somewhat by describing the mechanism at work. People without ADHD have a generally-working motivation/reward system which is undergirded partially by dopamine. This neurotransmitter is relatively low in ADHD brains, which seems to lead to signal:noise issues. That’s likely a cause of having a highly distractible baseline state, but also leads to bursts of dopamine seeming more salient and arousing. You have a harder time regulating motivation and evaluating perceived rewards. A lot of what happens in the brain is based on relative states. If your dopamine is always low, something making it spike will seem more interesting than it necessarily should. If your dopamine trends higher, you’re going to have an easier time regulating interest, motivation, and an ability to transition through things you need to do — particularly things you don’t want to do. The inverse of a dopamine spike is a dopamine drop. This impacts the brain in important ways as well. In a person with ADHD, going from a high to a low can often cause serious declines in mood and energy. In a more typical brain, the same effects are present but less severe. So while these are all normal challenges people face because they’re the product of the same brain mechanics, a low dopamine baseline makes these mechanics more extreme in people with ADHD. They are primed for distraction and clinging to things which increase their dopamine. This could be video games, relationships, drugs, hobbies, etc. It could even be work too. They’re also primed far harder falls from their highs. This extreme oscillation often means some aspect of life suffers due to a lack of balance. That’s why it can be a disability. Hopefully that helps explain the quantitative aspect.