It’s not guaranteed that the value of securing the network will be worth its cost even if the value it provides is very high - the cost could be many times high

It’s not guaranteed that the value of securing the network will be worth its cost even if the value it provides is very high - the cost could be many times higher still! I don’t say to this to argue that the energy consumption either is or is not worth it, just calling attention to a gap in your logic here.