Fair enough. I guess it's easy to sit back and be like "if I had that kinda talent, I'd quit my job digging holes and filling them in" not knowing what it's really like.
Or... are those manga about highschool manga artists correct and the average Japanese is just good at drawing? Reminds me of college with the recreational soccer leagues with dudes from Brazil / sub-Saharan Africa tearing it up but if you asked any of them they'd say "back in my country, I'm below average at football" XD
Could also just be the amount of work + Payoff = Not worth it.
I know you can (could) buy his work on Amazon and Kindle (translated) so it must've made a good amount. I think sometimes it's just pure burn out.
You see it with so many artists now where before they would never take breaks or hiatus but now it seems like every other artist does. There are just so many manga artists now that the market is oversaturated and mangaka's have to work even more to keep relevant.
Look at Yuri, it used to be pretty niche when I started reading it back in 2008, now it's mainstream and suffering from mainstream pressure.
Like you alluded to earlier, the content they need to add to make it past 3-4 volumes. If they don't have edgy stories, tits & ass, sex everywhere, they can expect low volume numbers and sales since now the bar is set so high due to the influx of people into the genre. I know this isn't 100% accurate but to say it's not a factor is just being blind.
Unless they have god-tier art and get picked up by a major publisher, it's pretty much a 2-3 volume expectancy.
I do like how the new model for like pixiv comics and that other comic site(s) (forget the name) has enabled lower popular authors and high pop authors to publish a lot more without as much pressure. For example the manga "She Likes to Cook and She Likes to Eat", the author is able to release whenever she feels like it. I think this is the best approach.
Sorry for the long rant I was bored and felt like writing lol.