Are Altcoins dead? This question is not easy to answer, because the cryptocurrency market is a very volatile one and there are many ways to capitalize and invest in isolated coins.
One can't just conclude that altcoins are dead. We still have a lot of altcoin doing well in the crypto space recently. Just that one need to be very careful in chosing which of the altcoin to invest in.
I think I would not blame someone being pessimistic on alternative currencies, to be honest, specially if such person has invested much of their time in project which have never given the expected results. It just takes to give a look at the story of most of the alternative currencies to realize that a very high percentage of them get flatlined and lose their relevance in a very short period of time after their release in the markets.
Truly useful and innovative alternative currencies will never be dead, cryptocurrencies are assets which are backed by code, by technology and technology never ceases to expand and reach new limits.
One just need to be careful what currencies are actually worth our attention and stay away from scams and shitcoins of all sorts. Even currencies which may appear to be legitimate and very solid at first glance, could be just shitcoins very good at keeping a facade, for example, we have what happened to the terra-luna ecosystem, which instead providing a reliable stablecoin without backing, they ruined lifes.