Display Moredepends on the idol of course but there are many popular idols but they generally branch out into different elements of the entertainment industry...
for example have you heard of SHE? or TF Boys? or F4?
but singing and selling songs is not as profitable as the other money earners such as acting or variety shows...
variety shows regulars make a killing....
no i haven't but it seems common in all countries where actors are considered top tier...