51% attack doesn't matter.... They would have to go back remine empty blocks and that's money wasted on energy. Then they have to catch up to the live block's being mine and then they would have too hard fork. And who is going to follow them.. And let's say if they take 52% of the network and and they block tranxactions. What makes you the other 49% of all of others are Not Gonna Validate your transaction your transaction will just take longer... it will be a waste of money it make more sense if they just join the network get incentives.. And if you have 51% of the network why would you want to mess up the incentives because you would be getting most of the incentives