As it turns out, the majority of folks are just people trying to get by, and if you're nice enough to them, they'll be nice enough to you.
The problem with most terminally online people is that their social lives ended when they left school, which is when the population of arseholes is at its highest. Everybody is trying to impress everybody else, even at the cost of others.
But a lot of those same people tend to chill off as they mature into adults and become less self-centred. There are still absolutely arsehole adults, but nowhere near as many as the terminally online expect there to be.
What do you count as terminally online? I don't differenciate between online and offline friends and spend lots of times talking or chatting to people online (as I spend time doing stuff with people irl). But I wouldn't say that my or this social life is bad.
I would classify "terminally online" as almost exclusively interacting with people online with little to no IRL at all. A bit part of that would also be that the people you interact with are people you've never seen.
I’ll also add another major sign is if you don’t know their irl names. I have close friends who I met over the pandemic who live far away, but we knew each other by name and hear each other’s voices. That’s a big thing. Your Twitter/tumblr mutuals or people you regularly interact with on Reddit/Lemmy are people that terminally online people will think of as friends rather than “no we’ve never met irl but we play d&d together or have a book club over discord”.
The other big thing is whether or not you go to irl events. Just literally being somewhere that’s neither home nor work/school helps so much.
no we’ve never met irl but we play d&d together or have a book club over discord
To be fair, DnD is one of those things I would never ever even consider playing over discord unless I considered you a very good friend, and even then it's begrudgingly. Discord dnd sucks balls.
I'd call people that who lost contact with reality. So if something you believe could be immediately proven wrong by just stepping outside for a while, you are terminally online.
For example the 4chan theory of: "80 % of women date only 20 % of ultra chad men". There are people who actually believe this.
Dating apps were mainstream long before 4chan existed, although not as dominant. The idea that all of the women go for the top tier of men gained prominence with an analysis posted on the old OKCupid of their user behavior, and the particular 80/20 split was just pulled out of somewhere, likely borrowed from the Pareto Principle. In any case, 4chan may have pathologized it, but certainly did not originate the notion.
My definition is more or less the same as the one @ParsnipWitch offered...
The terminally online are thise who have little to no contact with reality. They are the shut-ins and the NEETs of this world. Those that would fully believe in conspiracies about life which could be disproven simply by interacting with others IRL.