Like purchase multiple albums, donate to campaigns, stream, spend lots of time voting etc?
No there's no pressure on them this is just a fan mentality to do that. No agency nor idol suggests,implys knowingly or unknowingly pushes this. Alot of fans suffer what I'd call army syndrome. Yes I'm using my own fandom for this.
A lot of people live their lives through BTS and attribute the idols success in any endeavor as their own personal success they get a legitimate dopamine hit from it. This is why Alot of fans will do things even at their own expense like typing up their devices they need to use for zombie streaming, going out of their way to push music sales like buying 100 copies of the same album knowingly losing hundreds if not thousands of dollars despite needing that money for essentials. You can read hundreds of testimonials from parents here in Korea concerning their teenage and young adult children obsession with kpop especially when it comes to spending or time invested when they should have been focusing on school and let their grades slip because they have to attend every fansign and see every vlive etc. Now obviously this behavior is not indicative of the entire fandom but a generously large amount continue to do this this also happens in every fandom for any idol regardless of who they are.
Same reason we have idiotically pointless fan wars it's the same as sports team bravado literally no reason for it 🤡🤡✋.
