Not to be racist, but it always seems to be the Japanese who are at the cutting edge of these weird psychological deviations. Japan doesn't even make the Top 10 in population density though, so there must be other factors at work also.

One factor is the country has to be rich enough where there are parents who will actually keep supporting these cave dwellers. This is the ultimate in child-as-parasite behavior. What would you do if your 15 year old son refused to leave his room? For a start, I'd stop bringing food to his room. Then, if he has TV, computer or phone, I'd take all those away. How many of these kids would stay in their rooms with no food and nothing to do?
Definitely a failure of parenting here, but that begs the qurstion of why so many Japnese are crappy parents? Opinions welcome.
https://www.cnn.com/interactive/2024/05/world/hikikomori-asia-personal-stories-wellness/
A shrinking life: Why some Asian youth withdraw from the world
RE