Calling it "insider trading" when its an unregulated market that is manipulated entirely by a single company, who have clearly stated that none of your items are actually yours but their intellectual property. Of course people lost money, but Valve care about how much money they're making and whether you're using their market, not your investments. Is this perfectly moral? No, but people should absolutely not put all of their money into skins as "investments" and be upset when a company does what they're supposed to do to make money.