Miners are the only source of continuous downward pressure on the price, there are other sources of course but miners are nearly clockwork steady sellers, so the market gets accustomed to this effect. all they have to do is let up a tiny bit. the standard narrative is that they can't afford to do so because of the balance between diff rate adjusted mining costs and market price of the mined coin. What I'm pointing out is that because of the massive amount of head start they had from a decade of largely unpoliced mining wherever they found an "opportunity" to do so, legally or not, (as well as continued theft of resources to mine even today), they have plenty of extra reserves to use to cover costs, (assuming that they even pay market cost in the first place - see also: corruption) selling coins at today is prices which were mined at one, two, three+ years old cost rates or less.

This is not even getting into the circus known as tether, which I believe is a significant factor but actually quite a bit of an over-stated red herring serving (along with constant exchange clownery) as a distraction away from the much bigger influence that is the enormous subjective control miners have over the order book price of the coin.