the claim is that 70% of the hashrate is using Bitmain's hardware.
proof of claim? please dont refer to reddit or twitter
I have no proof of that claim, nor do I claim that it is true. I am simply stating that that is what people are saying, not that they are saying that Bitmain directly controls that much hashpower (which is what you said).
Seems pretty likely though, considering just how dominant BITMAIN is over that industry (very).
No one could realistically claim that BITMAIN
don't have too much control. If they managed to cause a problem with other people's miners (which they probably could) they could use their own vast mining power to do a 51% attack.
Decentralisation is necessary in
all aspects of Bitcoin.