Are cryptocurrencies centralized?

Are cryptocurrencies truly decentralized, as many proponents claim, or do they actually have elements of centralization that undermine their original purpose? For instance, is it fair to say that the development and maintenance of major cryptocurrency networks, such as Bitcoin and Ethereum, rely heavily on the actions and decisions of a select few individuals or organizations? And furthermore, does the increasing adoption of cryptocurrencies by governments and financial institutions signal a shift towards a more centralized model, where these entities wield significant control over the network? These are the questions that we must grapple with as we explore the true nature of cryptocurrencies and their potential impact on the global financial system.