I don't know the science behind ADHD either, but based on what I find people self-diagnosing themselves with ADHD based on, I always say that nearly everyone should claim to have ADHD at this point. Attention span is one of those things, apparently, and it's hilarious because in the age of social media where it's literally "Interesting or I scroll", you wonder how our attention spans won't get fucked up.
ADHD aside, I think social media has a huge role in conditioning us to forcefully diagnose ourselves with things to like you said, explain behaviours that are simply consequences of our lifestyles, and not medical conditions. People hide behind even things like depression or mental crisis to be shitty people, and because they have a certain TikTok creator or several who constantly reasssure them they're not the problem, they're convinced.
I don't see a lot of Africans identifying with ADHD. Makes me wonder if we're just not enlightened enough, too simple, or if it's that our plate is already too full to add things like this.