True, I think though that it becomes unethical if you're going to screw someone over.
It reaches a point where a person is getting screwed. Not on ebay because, the person buying says they are willing to pay this much, they could always not have said $2,000. When you scalp a ticket, sure you can haggle (depending on the situation) but for the most part the price is being dictated to you. And thus, you can get screwed, I've never been to a concert I didn't travel at least half an hour to. what am i supposed to do when the only scalper i see says $150? go back? nope, bend over and take it.
slight difference, but it's there.
Also i'd say someone is being a real d!ck head if there going to screw someone over on something that they also love, or are passionate about.