It is a shame that the hikkomori is a trend and becoming popular with COVID.
I think the relevant question is “why are people dropping out of society in greater numbers than ever before? What changed?”
Why not?
You grow being told that you go to school, you get the high grades, you get the good job, make friends, marry the girl, pop a few kids, and you're happy.
But it's never enough. There's always something you did wrong, always more you need to do right. You force yourself to do the things you're expected or you're forced to do the things you're expected to be happy about even when inside you're inside you scream and weep and want it all to just go away. Always more you must be doing it.
Hold on, they will tell you. Things will get better if you keep going, they will tell you.
You look at all the fighting at home. There's never any laughing or fun talk; you dread coming home because one wrong word or a wrong look and it's more shouting. This is what being with the girl you love is like? Turning home from a refuge into a place of fear and terror?
Hold on, they will tell you. Things will get better if you keep going, they will tell you.
Ultimately that turns out to be fine for you. You can't really get bring yourself to really befriend anyone anyways. You have nothing in common with anyone else. You have nothing you can say and nothing you can do that would make their lives just that little bit better. So you say nothing. And you do nothing. You just keep going on and on to the next thing and the next thing after that.
Hold on, they will tell you. Things will get better if you keep going, they will tell you.
But five years later on, and it didn't get better. Ten years on and it didn't get better. Twenty five years later and it never got better. On that day you realize what a sham it all was. It never got better, and it never will get better. They were lying to you all along. There is no better tomorrow.
And then you realize something else. Maybe that's fine to. The sun rises, other people laugh and play, and the world moves on whether you're there or not. So you just keep doing it. No hopes. No dreams. No future. Just never ending Now where you just survive the day, only to wake up and do it all over again until you don't.
So... after all that. Why not?
I realize that it might not help answer why more and more might choose to do so. I can't really offer answers to that. I can only answer why one person might choose to.