Koreans don't put fan death on some kind of nationalistic pedestal of overdramatic belief systems that make you Korean. If we wanted nationalistic symbols, we already have plenty---starting with Dokdo (a.k.a. Takeshima, but don't utter that word in front of a Korean), the "East Sea" (more commonly known as "Sea of Japan"), and... but I digress.
Koreans believed fan death because their mothers did, and then their mothers did, and also the 9 pm news used to say "Yet another person found dead next to a fan" every summer, because in a hot, humid country of 50 million people someone is going to be found dead in a hot day next to a running fan.
How could it be a "national identity", when the very concept that some people might not consider sleeping-next-to-a-fan as deadly was beyond people's imagination. (Remember, it was time before the internet.) Now, thanks to the internet and everything, (I hope) most Koreans know that "Fan Death" is a silly urban folklore. We even scored our own Wikipedia entry. Nice.
As I said think of it more like regional pride in barbecue. People from memphis don't think their barbecue is their identity, but if you insult it or say that Memphis barbecue sucks they defend it about as much as I have seen people in Korea defend fan death when my friend questioned it.
National identity is great, I guess, but at some point, it becomes actively harmful not to call out stupidity when it presents itself so flagrantly.
If it takes social pressure to get people to stop believing absurd things, then so be it.
Even if you don't agree with that statement, it's what people who prefer imperial units will say, not that there's some mass delusion / patriotic identity.