I'm new to the cryptocurrencies world and I'm trying to understand how all this stuff works, so expect a really noob question.
Suppose there's a user which generates a number of addresses and sets up his private blockchain. One of this address will start illegal transactions moving money that doesn't really exist. Since the other nodes of the network are controlled by him, the transaction will be validated. Now this address is moved from his private blockchain to a public pool.
How does the blockchain knows/prevents the malicious node from spending money that are not really there?