I was in the trade in/trade out world for a while, and it's really not so bad. You buy them used, try them out, and sell them for pretty much what you paid for since there's no real depreciation once they're already used as long as you keep them in good condition.

Part of it is a lot of fun. You get to try all these new headphones and only really pay the shipping cost. But at the same time, it's a bit silly. Yeah, it's a hobby, but it's not one that many people understand and especially my girlfriend at the time and now wife would certainly look at me and say "another headphone??" and then I'd have to explain that I'm not alone, there are dozens of people like me online trading headphones back and forth and it's just so I can listen to new stuff. It's not costing me that much money to do this and it's just a hobby.

So I settled on the K7XX a back when they came out and I've been using them ever since. I've really enjoyed them.