I would like to ask why nodes, which serve blockchain across the network do not try to manipulate with blockchain? Let's say 70% of them agree to insert fake blockchain into a system. What is the mechanism, which would protect 30% of honest one to kick bad guys out?
Could you explain this to me, thank you.
Nodes DO NOT trust each other at all. Every node has their own set of rules that they follow and they will verify every single transaction and block to ensure that the rules that they dictate is followed. If the rules aren't followed, the block or transaction is invalid.
I don't really get what you mean by
fake blockchain. If you are referring to the blockchain having coins that are created out of thin air, it is impossible. The nodes will verify that every single transaction (except the coinbase transaction) has a valid UXTO that it spends from. If it doesn't exist, the block is rejected. If blocks generates more Bitcoins than the current reward (12.5BTC)+ fees, it is also rejected.
If you are talking about creating another alternative blockchain and making nodes follow them, it is also impossible*.
* Nodes follows the chain with the longest proof of work. Unless you can outpace the network with a chain that is longer and has more difficulty weightage, follows the protocol rule, you cannot broadcast 20 blocks using 90% of the nodes and expect the 10% of honest node to accept it.