They sold premined ETH with ICO. Bitcoin never do that.
Beyond decentralization, this is what makes bitcoin apart from the rest of the market. Bitcoin was created with the intention of being a peer-to-peer currency, Satoshi did not intend to create bitcoin to be a profitable tool like altcoins, but we made bitcoin an investment asset. Meanwhile, ETH and all altcoins are created for the purpose of creating tokens and raising capital. Obviously, their original goal was to turn them into speculative assets, so it's not hard to see why they've become so centralized.