Why do you buy used CD's?

[cassette]

In this modern era of all music being free if you spend the time on the web, why do people still buy used CDs? I spend a decent chunk of change buying new stuff from artists that I want to support. But the artists get none of my money from a used CD purchase.

The only reason I could see for logically buying used CD's is if you are trying to help out the person or store selling them. Other than that, seems silly.