Miners, stop selling privately. Here is why it is not in your best interest:
-Miners typically need to sell their coin immediately as they have invested in equipment that expects a return
-There are deals for fixed liquidity privately. Where the miners can sell their coins outside the open market at a premium or at a guaranteed price range for a set period of time
-Those deals exist because there are market makers who profit immensely from pulling wool over the miners eyes
For example: the maker can buy 10,000 coins privately, which reduces the volume on the public order books. They can then splash the thinner books by selling 2000 coins; thereby bringing the price down. Now they can continue negotiating with miners stating that the market rate is $X - which is significantly lower than the market rate had the miners just sold on the open market. The makers are intentionally trying to keep volume off the open books so that they can keep the price low so that they can continue buying their coins low. Someone with $20,000,000 they want to invest in bitcoin would be able to acquire many more bitcoins by using the above methodology.
I dont get what you are trying to say, isn't selling it one exchange and selling it private the same?
I would personally argue that it is, however the OP seems to disagree.
If you trade privately then the person you sell to will either not purchase bitcoin on an exchange they otherwise would have bought to or will sell bitcoin that they would not have otherwise sold
Which results in the price you or I see being inaccurate, because activity is going on but it won't be reflected in the public price we're seeing on any open exchange. The OP's logic is accurate, whether it's actually happening is another story. I don't know enough about how many miners there are to know how realistic this scenario could be.