This is reasonable, lots of devs. those who left their projects when they were already making big profits, they preferred to make new projects rather than make their projects grow because managing old projects was difficult.
I am agree with you. Most altcoin worth zero because they can not continue the project they promises. Invest in altcoin sometimes very risky but when the project work and start having a product, its profitable.
Most of them are worth zero now but that is just a temporary thing.
I don't believe that they will die and disappear in the market because I have seen even shit coins in the past that came alive when the bull run comes.
Let's just say that team does not hype them because they know it's a bear market and it has no effect anyway.