You hit the point that there are too many people who don't understand how the market really works, but at the end of the day there will need to be more altcoins to purchase with fiat in order for the the market cap to get into the trillions of dollars. It is inevitable that Coinbase will list additional coins at some point over the next 12 months, which will really help with the fiat pairings for other altcoins and it should be pretty realistic that Robinhood will list more than the usual top few coins for purchase with fiat once they get their crypto platform running and work out the initial kinks.
It is all about how easily accessible crypto can become to less risk inclined investors. If people know they can purchase different crypto through a broker that is backed by the FDIC and it can be easily accessed and held in a portfolio with other traditional stocks, bonds, mutual funds, and ETF investments, the trust is then established to an extent for additional investors to put money into crypto. If this does happen over the next year or two as more brokerage firms see the money to be made in offering crypto investments, we can expect the entire crypto market to soar into the trillions.