[yokem55]

Ultimately, proof of stake has the same property. The value of the network that the stake protects is rooted in some kind of real world value. The tokens from the network can be traded for fiat money that is worth something. So, unless the value of the network being protected falls to zero, the stakes themselves are worth something. An attack on a proof of stake network still requires the resources to procure the attacking stakes. So, you still have a direct relationship between the item being protected and the cost of the protection.

[yokem55]

I would add - by focusing on using the economic value of electricity and stacks of special semiconductors to secure your network, you actually are making the network vulnerable to folks that can effectively create arbitrage on those specific narrow resources. In contrast, proof of stake can leverage a much broader range of economic resources that have far fewer arbitrage opportunities.