Nothing happened randomly lol. All you gave are theories based on biased researches. There are a lot of Articles explaining the growth of Kpop in America. They all acknowledge BTS big influence but none of them say BTS is why Kpop was getting more followers in America...
So you wanna say you know better why Kpop got bigger in the US then people who work within the US music industry?
https://www.google.de/amp/s/ww…oding-united-states%3Famp
https://www.google.de/amp/s/ww…r-american-pop-mainstream
Billboard
“And even without much radio play here, K-pop’s influence is rapidly growing. As social media and streaming platforms have evolved, so too has an ultra-socially engaged fan base -- one that not only devotes entire Twitter accounts to sending its favorite artists up the Billboard charts but also buys out arenas to support them and tunes in to splashy TV specials just to catch a glimpse of them, sending Korean acts ever nearer to the forefront of American pop.“
“In 2016, China’s dissatisfaction with a U.S.-South Korean missile-system agreement led it to ban all hallyu, or Korean pop cultural content, most prominently K-pop. It was a financial hit to the three main K-pop companies. Some continued to approach China with non-Korean acts, but others focused on sending their artists to burgeoning markets like the United States.”
So many things happened between the 2. and the 3. Gen then had an even bigger influence in the Growth of Kpop in the US.
Social media ( Twitter, YouTube, Instagram) fans were spamming their faves everywhere. Easier access to new content around the World.
Korea loosing China forced them to try America again, this time with a better approach... there is more, these were just examples.