its worked out that there is about 80exa of 'farms' and upto 60exa of smaller groups. which is why you see the hashrate peak at 140exa but drop to 80-90exa because hobby miners are jumping in and out at a whim.
Overall a great response thank you. And that quote right there ^ is exactly the kind of thing I was curious about. Assuming accuracy, that means that really only about 60% (rough number at that 140exa) is actually these few big mines that I was referencing, and almost 40% is made up of much smaller. Assuming those numbers are correct, that paints a much better picture than what's easily assumed these days. Thank you again!
This is not a valid reasoning to call bitcoin is a centralized coin as 10 pools are getting 90% of new bitcoins. Firstly because the new coins generated are now negligible to what is already in circulation and it's 90% is further more divided into 10+ pools. A large amount of coins (40%) are held by a thousand addresses, which still is much decentralized that fiat money in the world.