I too was making similar observation some days ago. What hit me is if currently 1000-5000 new S9 or equivalent are turned on every day, where they come from? Obviously its nearly impossible to buy new miners, at least on short term, if you are lucky and are able to order you have to wait months. some of these numbers could be from old miner models being turned back on again, others from some s9 getting delivered from old batches. but anyway numbers seems huge! Can it be that the miner factories (avalon, bitmain etc) put most of their production into their own farms? or can it be someone made a more effective miner (like n10 chip) but does not offer it to public and just use it for own farming? Ideas?