All those regular sellers are most likely the miners, who have to quickly move their bitcoin to cover mining costs. In an unfortunate feedback loop, the cheaper the coins cost, the more of their production they have to sell to cover expenses.

The price is dropping to the point where it's barely profitable even with the newest hardware, unless you're using it as a roundabout method of money laundering (sell coins for USD, pay your electric bill in RUB).

I thought "barely profitable" was what a free market will do to any resource.