Japan tends to be the canary in the coal mine for modern civilization. Whatever happens in Japan tends to spread to the West with about a 20-year time lag. Japan has been in an economic stagnation since the early 90's; in the West, only since 2009. Japan has had recluses since the 90's, and now we're seeing the same phenomenon spreading globally.

I think the modern male withdrawal from society is a massive and unacknowledged trend that will only accelerate in the decades ahead, and there is no simple cause. Macroeconomic trends, labor market changes, sociocultural changes, the accessibility and ubiquity of digital entertainment, all contribute to make social participation appear not worth it for a large number of men.