I do not believe bitcoin falls on the $ 400 price. You are in too much of a hurry to make a conclusion just because the current market is falling and will make bitcoin fall to $ 400. I would rather believe the $ 400 price would not happen on bitcoin.
I think now mining cost of Bitcoin is $5,000. Miners are getting less. Bitcoin does not have any use, it has just become a speculative asset.
I read that shops/stores sell Bitcoin immediately and get cash because of fear of price change. So shops/stores are the biggest sellers of Bitcoin.