I recently got to know about this too. In fact, I wrote a post about when Kang Daniel's fan did it for his birthday.
https://steemit.com/prameshtyagi/@renutyagi/wanna-one-s-kang-daniel-health-and-fans
Kpop fans even donated to a charity that he has shown support towards for his birthday.
https://steemit.com/prameshtyagi/@renutyagi/kang-daniel-s-fans-donate-to-celebrate-his-birthday