I still do leave my house, I have a job that requires me to be in the office for two days a week, but it's something I dread every single week for a variety of reasons. There's something bizarrely comforting about just staying in your bedroom all day and pretending the rest of the world doesn't exist, and it's kind of addictive.
Going outside and having a social life is usually worth it, but it's also kind of intimidating; I have to take a shower, get on the train with a bunch of strangers and not do anything too weird because of course I care a tiny bit what these strangers think about me for whatever reason, go into an office with people who are not-quite-strangers and work extra hard to not be too weird or say anything that might upset someone and keep my desk clean and have meetings with managers who could fire you immediately for any reason they want...it's all exhausting.
I still try and make an effort to leave my house sometimes, but I kind of get why hikikomori do it.