How much is Web3 worth?

Can you tell me, how exactly does one go about valuing Web3? I understand it's a concept that encompasses decentralization, blockchain technology, and token-based economies, but what metrics are typically used to assess its worth? Is it purely based on the market capitalization of cryptocurrencies or is there more to it? Additionally, are there any notable projections or forecasts available for the future valuation of Web3 and its impact on the global economy?