Why Is Proof of Work Considered Secure?

Proof of Work is considered secure because it makes altering the blockchain incredibly difficult and resource-intensive. To change a transaction, an attacker would need to redo all the complex computational work of the blocks that came after it, which requires immense computing power and energy.

This computational hurdle ensures the integrity and immutability of the blockchain. The economic cost of such an attack, requiring control of over 50% of the network's computing power, makes it practically impossible for most actors.

This system creates a trustless environment where transactions can be verified without a central authority.