As a relatively young market, crypto does not have a history of data to provide analysts with value justifications. As a result, many theories about the future value of top coins and the market as a whole rely on comparisons of the current crypto market cap against more established industries.
The total market cap gives a general indication of the popularity of the idea of crypto. For instance, the market cap during the 2017 mania reached almost $900 billion according to CoinGecko. That peak coincided with the highest instance of Google searches for crypto-related terms on record and the most aggressive movement of investors into the crypto space.