You can't truly be full neet and happy. I've been full neet since COVID, and I go out once every 2-3 weeks to go to the library to studymaxx, but besides that, I don't leave the house during the day whatsoever. This lifestyle makes you lose your sanity because you abuse all your coping mechanisms until they don't work anymore. For me, it was anime and games, but now those just don't do it for me anymore, so now I spend my days daydreaming about a different life where I got everything that I wanted in life.