Just a thought. Of course its decentralised by an order of magnitude compared to fiat or other alternatives, but what about the process/team that decided the 21 million coin limit for example? How are such rules changed by the way? Is it the same dev team that pushes changes to the Core release that decides these things?
Bitcoin is decentralized which means that almost any rule/protocol/design could be changed by almost anyone, and this is working exactly as intended as is the nature of anything that is truly decentralized.
However once code has been changed it stops being Bitcoin unless that change is supported by most of the community including miners, devs, holders and other stake holders. If however there is not enough support then it simply becomes a fork of Bitcoin and its future success or failure would then depend on how much community support it gets. ( think of the B Cash fork, BSV etc which did not get enough community support and was not able to hijack the BTC ticker despite the best attempts of many very influential stake holders roger ver for instance to do so).
As such anyone could go on to Github and submit a BIP proposal for implementing a change/ improvement in Bitcoin. But more often than not these proposals are discussed meticulously for long periods of time before they are actually able to get enough support to be implemented.
Attempting to change 21 million coded cap would be very contentious to say the least.