> Isn't the "weak guy becomes tough guy" power fantasy make the majority of the manga market, at least in the west?

Shōnen is probably the bigger market, but it’s worth noting that the key to the “style” is that it’s the term for the target market: young boys. There is usually a power accumulation fantasy, but more accurately these are typically coming-of-age stories.

So:

Shōnen: Young Boys

Shōjo: Young Girls

Seinen: Young Men

Josei: Ladies (there is also a separate category for “Young Ladies”)

As you can see, these are less genre terms and more demographic terms.

They’re different kinds of power fantasies. The one in webtoons is called “naroukei” in Japan, has more self identification and a dark brooding incel hero, and implies you’ll get a girlfriend by being really good at video games. Most popular Japanese example is SAO, although the author of that has lightened up a lot and is woke now. (The fantasy novel “isekai” variant has a strange tendency to have the MC buy sex slaves and the author to explain why it’s fine actually.)

Jump comics are the best selling manga in the US, but the brand basically works by having a few big magic power based series (Demon Slayer etc) that draw you in and then a lot of other ones in different genres (Spy X Family is a family comedy). Also, while none of the editor staff are or ever have been women, these are actually appealing to girls.

Rather than a single self-identification MC, Jump’s magic battle shounens tend to have very large ensemble casts who simultaneously have unique superpowers and are in some kind of corporate org chart power ranking. It’s unclear how they figure out that the guy who can turn into lava on Thursdays is rank #5 and the guy whose shoulders are drums and when he bangs the drums your head explodes is #28.

That is increasingly less the case, thankfully. These things do take time though. An interesting parallel is the French market for translated manga, which has a much higher diversity of series in non-shounen demographics available. Hard to know how much of that is due to the French actually being more interested in these demographics, and how much is American publishers believing that manga targeted at other demographics is likely to be less successful and hence mostly going with safe bets.

Additionally in manhuas, some non so usual topice are overreepresented, like a _lot_ of shonnen manhuas about business character success/CEO kind of stuff.

That’s normal for Korea - Kdramas do it all the time too. Not so much in the West.

> Not so much in the West.

There are plenty of soap operas that feature similar plot lines.

Maybe that's because the distributor thinks other genre of manga is so fringed that cannot generate enough revenue to justify the translation?