Is Bitcoin a Decentralized Currency?

Bitcoin has achieved popularity by promising users a fully decentralized, low-cost virtual currency system. A limited set of entities controls Bitcoin's services, decision-making, mining, and incident resolution processes. These entities can decide Bitcoin's fate, bypassing the will of the multitude of users that populate the network. Bitcoin has led to the emergence of several centralized services that take up a considerable share of the Bitcoin market. Bitcoin resists double-spending attacks by using a distributed PoW-based service. Bitcoin's core developers have the authority to modify Bitcoin protocol and all radical decisions require consensus among all the developers according to the Bitcoin Github repository. Bitcoin users do not have direct influence over the administrators' appointment, raising questions about universal appeal of Bitcoin.