If you were asking how many people buy four CDs every week, you would have a point, but people often bunch up their purchases for many different reasons. Buying five CDs once a year shouldn't be impossible.

I've bought 11 CDs in the past week, with another 3 in the mail. Might be something of an outlier though.

CDs are a lot less expensive than hardcovers or newly-released video games, especially if you buy them used.