Even in PC building for gaming, I never cheap out your PSU.
I am not a crypto miner, but I had kept this in mind for plenty of years of doing my hobby of PC building. Usually when getting PSU, I stick to reputated brands like Corsair, EVGA, Seasonic, though that does not mean that you won't have bad PSU, the chances of your PSU being a ticking time bomb is just unlikely.

I can still recall back in the days when my 4 pin ATX power connector burned then I realize that it was like one of those flexible cables that you're talking about there. Good thing it did not take my whole rig with it.