Why would you be angry at people paying real money for them? It's an ad-hoc currency, people use them because there is a sizable but forever limited supply. I think it's brilliant. I traded mine to a pleasant gaffer for a copy of Gods and Kings and I don't regret it one bit, I got a game I really wanted, he will get to flip them at a higher price later on or do whatever it is people do with these things besides wearing them. Win/win!
It's too bad you gave yours away. The more important lesson here is to ignore strangers who add you. On any service. Oh, and maybe from your TF2 days you have something else that could be worth something. Check out the Market under the Community tab on Steam to see what people are paying, and either sell it there or find a friend/gaffer who would trade for it. I don't actively play TF2 anymore, but I had a fun week of listing and trading my remaining items and making a bit of cash to buy more games with.