No there isn't. These ridiculous numbers are made up by taking the last price a coin sold for and multiplying it by all coins. If I create a shitcoin with 1 trillion coins and then sell one to a friend for $1 I've suddenly created a coin with $1 trillion in "value"

I'm not sure the 3 trillion includes shit coin valuations. Typically volume and liquidity are factored in for any serious analysis. Your assessment of valuation is probably just as true for traditional currencies and stocks. I guess the main difference is regulation.

3 trillion is just the top 5 or 6

Good luck with the SEC when you open your exchange

It's 2025, financial crimes are legal

Unfortunately, the amount of money invested in something isn't indicative of it's utility. For example: the tulip mania, beanie babies, NFTs, etc.