So what is going on? Where are all the sellers coming from? Twitchy day-traders or early adopters with big stashes taking advantage of better liquidity?
Anyone have any insights, ideally backed up with some evidence like days destroyed or exchange data?
My thoughts always gravitate to it being mostly to do with people just making a bit of extra money but more importantly more coins.
There are very few investments where you aren't trying to come out with a bigger pile of fiat, in general when you trade a normal stock you tend to buy a position and then sell (or buy if you were short) and leave with the profit.
With Bitcoin however people are trying to make more of the 'stock' than fiat (obviously a generalization but can you draw any parallels?) a lot of people are also all in in terms of how much they are willing to invest, to make more BTC and not more fiat without leverage you have to sell and buy back at a lower price. I seriously think this is one of the reasons people are so willing to sell their BTC for the chance to buy it back lower even though the majority of them would have been better to buy and hold.
Also, occasional and opportunist traders aren't keeping their fiat on the exchanges, so if there's sudden action the most efficient way (in fact the only way fast enough) to get money on is with btc. For example with Silk Road last year - when the news came out everyone saw there'd be a buying opportunity, but the only way to buy was to send over btc and sell first. You miss the first hour of the move (the price of security), but can still turn a buck.
edit: The implication of course being that when we finally get a "grown up" insured exchange, there will be less "flash crash" pressure because fiat will be happily left pre-placed