@checksum0 Lots of people have demonstrated there is a custody agreement involving Antpool, and possibly F2Pool, for smaller pools (quite a long list).
I'm theorizing Antpool are building blocks for them too (excluding F2Pool), thus controlling all the hashrate for those, by proxy.
Bitmain is also backing / financing a significant % of gross market hashrate (hardware + infra). They are also backing / doing sweetheart deals with lots of software infra.