The value of manga is really hard to put into a clear revenue value. Similar to Pokemon, the properties generate revenue in so many different formats, that the manga itself is merely a carrier for the property at large.
The merch, computer games, pachinko and anime add up to a significantly bigger value than merely $2 billion. For ex: just the 3 biggest recent manga movies: 'Demon Slayer Mugen Train, One Piece Red, Jujutsu Kaisen 0' made a total of $1billion at the box office.
I'm all for disruption in the manga business. The working conditions for the mangaka (authors) are inhumane and slavish. Early deaths and chronic health problems are the norm.
But, Korean webtoons are nowhere close to the quality or economic value of manga just yet. 'Peerless Dad [1]' is the only one I've found so far that I'd recommend to everyone. Ofc, there is a lot of tropey-wish-fulfillment in the likes of Overgeared, Solo Leveling & Sword king, but 2/3 of those have ended up in the dreaded K-manwha churning powercreep and none of them do anything particularly new.
[1] https://webtoon.kakao.com/content/%EC%95%84%EB%B9%84%EB%AC%B...