Why is Bitcoin not decentralized?

Although Bitcoin is the first and most popular cryptocurrency, it is not entirely decentralized as some people think. Its Proof-of-Work (PoW) mechanism and mining pools permit single entities to control significant percentages of the computing power on the Bitcoin blockchain. If a single pool can achieve 51% of the network’s computing power, it can conduct a 51% attack. Proof-of-Stake and Sharding consensus mechanisms distribute a network’s power across different individuals and restrict the amount of power a single entity can hold, making the underlying blockchains fully decentralized.