Bitmain becomes more and more SCAM. Shipping worthless Miners out. Miners were used for sure months before to mine the easy- profitable Coins themselves. Now after they are becoming unprofitable, they ship them out (more or less refurbished) and finally even overclocked.
To cover the fact that the miners will never reach POI, and will probably die even before warranty. Yes, Hashrate exploded in last time, and thats also caused by Bitmain (not only)
Sadly there are no profitable Miners on Market (50GH or more). Probably such exist, and are probably running in Bitmains Farms already until they get worthless. Then Story repeats