[kown223]

hmm.. what's happening is a bit of bitcoin weakness, a lot of hash power came in, raised difficulty and then left, 40% or so, tomorrow the difficult should adjust, the dangers of centralized mining, although these shenanigans may lead to a proof of work change.

[paulmd]

aka the "frisbee on the roof" attack, it's been a known danger for years. The danger is that the difficulty recalibration time is measured in blocks, not in actual time - so if taken to extreme levels such that miners drop out, there is no guarantee that recalibration will ever occur. And profit is inextricably linked to block time here.

(and note that "attack" in this sense is not necessarily deliberate in the sense of an attacker, if Bitcoin Cash or another coin suddenly becomes drastically more profitable for some reason it can occur naturally. It's more of a vulnerability than an actual attack. It's a state-machine state that is potentially non-recoverable without a coordinated fix.)

Bitcoin Cash actually includes a specific fix for this attack, which is why hashrate has been seesawing so badly between the two networks - BTH becomes unprofitable, the power moves back to the BTC network, then the frisbee fixer kicks in and reduces difficulty, which spikes profitability back up.