@DDAsics: Monsterer is referring to the "nothing at stake" (N@S) problem, which affects mostly PoS algorithms (but in his opinion also affects PoC). If there is no value at risk if you mine more than one chain, this opens the way to some attack vectors. In PoW, attackers always have costs when they want to carry out a double spending attack, but in PoS they can try so continuously, practically "for free". Also in PoC there must be value at risk to mine more than one chain, if it doesn't want to suffer from N@S.
There is less at risk than in traditional PoW, but not nothing; the point is that if PoC was carried out in an "industrial" fashion like Bitcoin mining then the loss of failed hard drives would become a major factor.
That is not value-at-risk in the same way as electricity cost of mining; what you are referring to is the marginal cost of maintenance, which of course all hardware has especially regular bitcoin mining hardware.
It is not exactly the same "value-at-risk level" (to call it that way). But if PoC was carried out in industrial fashion the marginal cost of maintainance would become dominant in the "attack cost" calculation, while in Bitcoin/PoW systems it's a negligible fraction of the total attack cost. Maintainance costs are external costs, unlike in (pure) PoS where the "attack cost" is tied to the price of assets created inside of the blockchain. Maintainance costs go up in the case you try to mine two or more chains at once, so there is value at risk, albeit not the same amount than in PoW.