It's an urban myth that Koreans believe that urban myth.

In my experience they do their best to propagate the idea that Koreans believe this myth.

I have yet to meet a Korean who wouldn't defend fan death.

Maybe it is like the Australian drop-bear.

It’s strange that in 2018, superstitious beliefs without any evidence are widely believed. It makes me wonder what kind of bizarre superstitions will exist 100 years from now.

I lived in Incheon for 2 years and can confirm that belief in fan-death is definitely not uncommon. I even have a couple Korean friends who can rationally explain why fan-death makes no sense but still reflexively leave the window open when going to sleep with a fan on.