Can you confirm that control of hashrate is decentralized?
The economic parameters of Bitcoin are well known and unlikely to ever change, there is no leader to authorise any changes, so the interplay between bitcoin price, and hash rate, and PoW difficulty is allowed to work itself out without any interference from any outside forces.
Bitcoin could be banned in every country on the planet, and the price would adjust as many stopped using it, and then so to would the total hashing power on the network adjust, and then the difficulty adjusts etc. This mechanism is known to everyone, and set in stone for Bitcoin, so all actors know the 'game', and as long as you accept that a total ban would be as effective as the war on drugs, people will always use bitcoin, and people will always mine bitcoin. This is the magic that satoshi created by disappearing.
So, to answer your question, Bitcoin hashrate is decentralized because miners are always free to enter and exit based on their personal profit/loss calculation, today it can be concentrated due to economies of scale, but those miners have zero incentive to break the system that makes them money, and even if they did try, and Bitcoin price dropped to $10 after a crisis of confidence, all that would happen would be new miners with cheaper costs enter the market, and the parameters adjust. At some price people would end up mining on cpu's again, the Bitcoin network doesn't need a particular price to keep it going , it will go on forever, even if it's illegal, because it is useful and nobody can control it.
The key is there is no Bitcoin HQ, or leader, or even dev team, we all own and control the Bitcoin network. This is not the same as any other crypto, most have dev teams and leaders who make decisions everyone else has to accept whether they like it or not, and those leaders can be harrassed by nefarious forces at any time. The Bitcoin governance system is perfect, because it doesn't exist, this is the paradox.