well your is even more flawed then, because you started with saying "if banks turning on(which mean buying) 300peta of hash", i answer in the same way, why they need to do this if they don't need money??
also it doesn't matter what is their intention(even if they want only to kill bitcoin), they will lose money doing it, end of story
No it is not. You have a wrong understanding of the possible scenario. If a certain % of people move to Bitcoin completely the banks are going to lose a part of their business.
That's how Bitcoin is a potential threat. They will lose money investing on their equipment to save themselves from losing more money.
well you changed the cards on the table, i wasn't talking about the future , i was talking about the present(notice how my calculations were based on current market cap, with bigger adoption there will be a bigger market cap, so banks need to invest like two more zero to my calculation, still not worth it...), right now it's not worth it to do a 51% not matter the intention and it will be the same in the future...
also if the majority will move to bitcoin, it mean that we reached mainstream status it also mean that nor the bank or the government can't do shit anyway, because to do a 51% account at that point would require billion/trillion of dollars or even more, and this isn't a thing that a single entity could do alone, you would need all the banks and governaments combined.