> The real number of users is likely considerably higher, the software being installed on pretty much any computer in South Korea.

This is a bit of an exaggeration. Plenty of young people hate this stuff enough that they do all of their banking through their phone and if they absolutely must do it on a pc, they either use an old disused laptop, do it at work, do it at an internet cafe (not that those don't bring risks) or make sure to remove the spyware the second they've completed the task at hand.