well, add some money for maintenance, breakdowns, tech support, protection (I know that mining installations require bodyguards in russia), bribes, wages, rent, taxes and that 600% goes down fast.
but all in all, I guess it's still a pretty good business after all costs are discounted
It does, but it also becomes insignificant when BTC breaks $100K.
also true, 100k would make all this bear market stuff worth it and will be life-changing money for a lot of people