You’re forgetting the most crucial and definitely centralized aspect of Bitcoin: the developers. Their influence over the protocol’s modifications outweighs a large sum of random individuals’.
The developers who are still around and respected are those who work within the protocol rules which are already laid out. That is, the bitcoin protocol can be modified through soft-forks which add further constraints to the set of rules accepted by some bitcoin clients, in backward-compatible ways with existing clients. The developers who have attempted to go the way of hard-forking themselves away from the rules by attempting to relax them simply get cut off from the larger network and they operate in their own niche (eg, BCH).
Bitcoin is its network, not its developers, miners, exchanges or anyone else who thinks they have leverage.