If you go to a bookstore and ask someone not particularly familiar with the industry to go find a comic book; you are very likely to have them hand a manga or manhwa tankobon[0] back to you. Trade paperbacks[1] are sold in bookstores, but the western comics section will be a small fraction of the manga & manhwa section.
The root cause of this is that in the 80s, comic book companies - say it with me, folks! - underwent massive amounts of consolidation to chase efficiencies at the expense of their ability to innovate and their ability to withstand systemic shocks. The particularized version of this is that the comic book companies ceded their cultural ubiquity to milk comics fans dry.
The efficiency being chased was "direct sales" - i.e. selling comic books to dedicated comic book stores, rather than in mass-market areas like grocery stores. A key thing to note is that the mass-market sellers retain the right to return unsold inventory and get a refund[3], but comic book stores bought on "all sales final" terms. What this ultimately meant was that comic book publishers didn't have to worry about the quality of the books anymore.
There was a long-standing cultural stigma in the US that comic books are for children. This was itself downstream of a push to censor comics that was partially successful and resulted in the Comics Code stunting the growth of the medium[4] in the US. Eventually, thanks to - among other things, Marvel wanting to publish an anti-drug PSA in a Spiderman book - the Comics Code Authority lost their power and we were able to publish comic books for adults in the US again.
Anyway, Alan Moore wrote a really gritty Batman book and kicked off a rush to capitalize on a growing adult comics wave. This, along with a bunch of people realizing that old #1s of comics published during Baby Boomers' childhoods[5] were super rare kicked off a huge speculator wave. The comics publishers - who at this point were just DC and Marvel - saw the dollar signs and started flooding the market with slop to meet the demands of speculators who were buying #1s just because they were a #1.
This continued until it could not. In an act of supreme hubris, Marvel decided to buy a comics distributor in pursuit of extreme vertical integration and wound up completely destroying their ability to correctly print a book. Then they went bankrupt, got bought out by a corporate raider, and sold their movie rights to anyone who had a buck. DC wound up in the hands of WB (lol), Marvel became a Disney property.
Yes, the 2010s comic book movie wave was directly caused by the 1990s comic book industry's death. And, for that matter, the exact same extreme consolidation that killed comics is coming for Hollywood. Disney bought Fox, Larry Ellison bought Paramount and WB and merged them into Skydance. The entirety of America's cultural industries are looking more and more like DC and Marvel fighting over the ashes of a culturally dead country.
[0] Japanese for trade paperback[1][2].
[1] English for tankobon[0].
[2] Okay, this term actually has two meanings:
1. A paperback that is not printed to mass-market standard. Publishers don't really do mass-market paperbacks anymore, even manga that is printed to mass-market sizes isn't priced like the mass-market books they are in Japan.
2. Anthologies of previously-published comic books - floppies in the western case, massive pulp-fiction magazine bricks in the Japanese case. Sometimes they're not even in paperback!
[3] Which, funnily enough doesn't even usually require returning the whole book, just the covers.
[4] The shit the Comics Code did to US comics makes the censorship changes in the 4Kids dubbed version of One Piece look liberating in comparison.