Why is it so difficult to tamper with blockchain? Actually, there are just two key factors—hash functions and the chain structure combined.

Let's break it down. Each block is like a box containing transaction records, with a unique label on it, which is the hash value. If you secretly alter any data inside the box, the hash value will change drastically. The crucial point is that the hash verification of the next block relies on the previous block's value. If you change the previous one, the validation of all subsequent blocks will fail in a chain reaction.

Even more impressively, the entire network isn't controlled by a single company but maintained by thousands of nodes. Want to tamper with the data? Sorry, you'd have to compromise more than half of the nodes simultaneously across the entire network, which would cost an astronomical amount. That's why mainstream cryptocurrencies like BTC and ETH can operate stably for so many years, with security that can always be trusted.

In simple terms, it's a dual insurance of technical design plus economic cost—both are indispensable.