[raulus]

4 reasons for me:

1) Selling dupes, typically after an upgrade to a nicer copy.

2) I thought I wanted to work on a set, and then realize that it's not my jam, and I'd rather focus on something else.

3) To get a card that I want, I have to buy a larger group, and now I'm selling off the pieces that I didn't really want, but had to buy anyway.

4) Sometimes I pick up something nice that I think is worth a lot more and is usually difficult to find. So I pick it up with a plan to someday sell it for more, or use it as trade bait for something that I want more. It's mostly worked out, although often stuff will sit for a long time, waiting for the right buyer to come along.