So you believe that bitmain is accumulating. I believe that they're selling, slowly but surely dumping their mined coins on the market. They have a certain amount saved up just in case it all explodes, but most coins are being sold. They have people's wages to cover, bills to pay. They aren't going to go crazy on trying to stop some idiot from selling his stash because he thinks BTC is dying. If you want to defend a price level start buying.