I describe myself as a hermit and have been for a decade or so now. I often don't talk to another person for months at a time (10 months last year). And don't live near anyone. I hadn't heard of hikikomori but it looks to be describing me.
As to how I got here, what drove me to the life was an inward spiritual search to remove all attachments to anything in the world, including the mind itself. To that end, socialising and involvement/investment in the world hindered the goal. Also being an introvert who works online with no interest in sex, relationships or having kids helped. Yet now I'm on the internet all the time, I have to question what the point was. I assume the next move will be to somewhere without it either.
In relation to suicide, I don't consider myself suicidal in the sense that others here are suicidal. But my goal is enlightenment, which is a state in which the body won't be able to function, and without anyone nearby to keep it alive, will result in death. So the end I guess is the same.