Wrong, bitcoin is not centralised but it's opposite of that. Bitcoin us decentralised which means no other 3rd party can alter the bitcoin network and government could also can't impose tax on bitcoin. All I know is bitcoin is automated and no one can change the system.
Yes Bitcoin is decentralized, anyone or the majority can decide whether they want to change protocol in Bitcoins Algorithm if necessary. But, it is still up to the Bitcoin Core Developers to execute those changes if they want it or not.
[T]here is a discrepancy between those who can provide input to the project (the community at large) and those who have the ultimate call as to where the project is going. Indeed, while anyone is entitled to submit changes to the software (such as bug fixes, incremental improvements, etc.), only a small number of individuals (the core developers) have the power to decide which changes shall be incorporated into the main branch of the software.
(c)
https://www.cryptocoinsnews.com/bitcoin-highly-centralized-network-says-harvard-researcher/