The truth is that bitcoin becomes more centralized last three years because of asics and china miners, but compared to fiat currencies it's still very decentralized.
Bitcoin has no central control: no central repository of information, no central management, and, crucially, no central point of failure. And yet, most of the actual services and businesses built within the Bitcoin ecosystem are centralized. They are run by specific people, in specific locations, with specific computer systems, and they are susceptible to specific legal entanglements.