Without real demand from real people, market cap. is a worthless parameter.
And what base currency is being used to buy these other cryptocurrencies? It's not supply limited Bitcoins, the demand is being fed by unlimited supply fiat currency (which just so happens to have seen huge supply increases over the last 8 or 9 years)
Just about every aspect of the metrics can be gamed, velocity of money could easily be faked also. At the end of the day, smart people will make the smart choice, and refuse to accept dumb choices. Who will lead, who will follow.