Anyone noticing new projects still raising millions of dollars? Mohash and Dynamic for example, I think new projects will replace lots of top altcoins in coming years and my advice to young investors is to find new projects to mix with their portfolio, remember that Matic, Polkadot, Avalnache are once all new projects in 2018/2019..
You also have to remember that these altcoins you have mentioned that's relatively new during those years were not the only project that's been introduced to the public. A lot of good projects that went down and a lot of scam projects that looks legit at first but only these alts you have mentioned became a good and top alts in the market.
It's not easy finding the best project during their early years.