This is a tautology. The hardware used to build a longer chain (a 51% attack) is hardware that is profitable to mine with. Thus you cannot use unprofitable hardware.
That happens in a 51% attack in the sense that that hardware could be used to mine and make a profit but instead it is funded by someone else with the scope of attacking the blockchain. (You cannot build a 51% attack with obsolete hardware)
Yes, but isn't the case today that it is hard to amass the amount of hash power that you need for a 51 % attack? If difficulty goes down drastically, hash power is there, somewhere, and can be powered up easily for malicious reasons.
Bitcoin and cryptocurrency is still experimental, everyone investing should know the risks and one of the risks is that we will never fix all the problems and Bitcoin won't work
the cost of a 51% attack is increasing constantly, I don't have the math handy but atm no nation state can pull such an attack alone and it will only get harder. Since it didn't happen even once I don't think we need to worry about it happening every other day
But if difficulty goes down to let's say 5 % of today's value, it might suffice to get in control of one of largest miners of today, no? Still expensive, sure, but maybe not for a certain goverment that would have large incentive to make the blockchain crash and burn...?
Thats assuming that miners are running at thin profit margins (which is not the case) and a 5% drop will make obsolete only 5% of the mining hardware. As it is mining is still profitable and it will an over 50% drop for your scenario to happen.
Discussion between Daniel R and Emil R
Discussion between Daniel R and Emil R