Volumes are lacking because the entire market is extremely thin - it requires a relatively low number of coins to get the market to sink badly. If you also take into consideration that there are huge loads of bots pulling back their 'buy support' at the time the price is about to fall within a certain range, the buy side of the orderbooks gets even thinner. Other than that, the market has indeed kept holding strong despite everything we had to swallow, but I still believe that we'll see every USD exchange dive below the $4000 level before the end of this week. The sentiment has changed, and the momentum that's needed to get the market to rush up further is gone - let's see how much value these words still have at the end of this week.