the altcoins have no demand. But some actually have demands, they are bought, their prices went up significantly but later they are dumped for other coins. One thing I have known about experienced crypto investors that like risks is that they will buy the new altcoins, their prices will pump. Later the new altcoins will become old and they will dump the altcoins for another altcoins. This makes us to later think that we can classify the altcoins that they have no fixed supply as new ones are getting created and old ones are dumped. When memecoins are getting created like the rate insects are giving birth now, it takes less than few weeks or months for a new coin to become old and get dumped. But like you have said already also, many of the coins are even shit from the beginning.
Unfortunately altcoins are not that long term in many cases, it is not that easy to handle. I understand it may not be easy for anyone to reach a conclusion that some altcoin can do great for the future. Some at the top could be doing fine, but they are not bought and sold quickly anyways, we are talking about big names and big deals. So it's clear that we should not be expecting a good return for memecoins or tokens or what have you.
Bitcoin is great, because it has fixed supply and it's decentralized, which means the people are in charge, us. Not the central bank, not the politicians, not the governments, it's us the people who decide its faith. Nothing like that exist anywhere in the world, maybe gold, but even that has rules that prevents you doing many things with it.