The value of pokemon cards or birkin bags is not because they are physically owned. This should be obvious from the fact that I could cheaply reproduce them and my identical reproductions would have 0 value compared to the original. I still own them though so again, according to your reasoning they should have the same value.

Some pokemon cards are worth so much i could reproduce them with gold instead of cardboard and it would be worth less than the cardboard version (assuming the same weight)

Please critically think of counter examples to your arguments before posting them.