Coin Review: In plain words, the United States defaulted on its debt because it still has to keep contracts, and contracts are more important than anything else. However, there are still some countries in the world that do not keep contracts. They can modify and tear up their accounts at will. There is no such thing as a contract. Some people even say that a contract is just a piece of paper. Unlike the Bitcoin account book, it is natural and cannot be changed by anyone. It is the same account for the whole world.