There's an enormous difference between things you "value", and economic value.
We probably value air more than anything else, but it's worthless.
Economic value = demand / supply. Simple.
It can be useful to think of economic value as a more abstract form of energy - a "monetary energy" - with the same conservation-of-energy properties. For example, if I create a TV that's better than all the existing TVs, the economic value of my TV is sucked from all the existing TVs which are suddenly worth less and contain less economic value.
We probably value air more than anything else, but it's worthless.
Economic value = demand / supply. Simple.
It can be useful to think of economic value as a more abstract form of energy - a "monetary energy" - with the same conservation-of-energy properties. For example, if I create a TV that's better than all the existing TVs, the economic value of my TV is sucked from all the existing TVs which are suddenly worth less and contain less economic value.