I agree K-Pop isn't as popular as the bubbles believe it to be in America. The comparison should be between S. Korea's vs Japan's sub-culture eg manga, web toon, live dramas, and music, and its impact on the West while taking into consideration Japan had an early start (and now established influence) on influencing for several decades. In comparison, Korea and K-Pop is still a baby. Another way to look at it is, Japan popularized Asian Animation (anime) in America the same way S. Korea did for Asian Music (k-pop). Japan's start was a cascading influence of video games, j-rock, and anime + manga. But you are right if we talk about music alone, k-pop is not as popular in America as fans think. S. Korea is still working on their cascading influence (k-pop, dramas, toons, web novels, esports, etc). Until then, we will see more Ahegao Sweaters.
Until South Korea has a rock band as influential as Loudness was for Japan in the early 1980s, K-pop and K-rock won't be relevant in the US.