I think they are fairly typical social media narcissists who like dancing and twerking on the Internet for attention and approval. There are plenty of young women out there like that, and nurses are generally known to be “crazy” - hyper-sexual in bed but totally emotionally chaotic and co-dependent. For them, Covid was an opportunity to be seen as “heroes” and “the greatest people of all” (narcissism, attention, and approval). And typical of young women like that, they immediately converted their newfound hero role into what they do best: shaking their ass for men. I also think they justified it as a morale boost during the pandemic, and then beyond that it was a fad like anything else, and young women are notorious for falling for every new fad as long as it has a big enough marketing push (the entire fashion industry relies on this).