Becouse they prefer pokemon battles
they are too focused on dumber shit like anime and hentai
esports isn't big in japan because of gambling laws or somethin
jPNs dont normally play PC games. And that one unnecessary gambling law prohibiting large prize pools.
Japan does not do PC games. They heavily love the arcade, which means they are usually into rhythm games or arcade games, which is why you will see a lot of top street fighter and tekken players being Japanese. They also love Nintendo.
Additionally, not becoming a salaryman pretty much automatically makes you be considered weird or strange, making you highly unlikely to get married in the future etc, unless you are very successful