Altcoins are the duplicate of bitcoin so, what do you expect, they will fade away over time, because their purpose of creation wasn't to help solve any problem which bitcoin cannot solve, but to use it as a means to extort people's funds. This is why shitcoins cannot increase in value, because investors are saving the value of their fiat currency by putting it into bitcoin investment.
Only gamblers, and people who don't care about their financial well-being of their future will invest in altcoins. One same person create a shitcoin and after dumping the project, he waits for a while and create a new project with a different name entirely but with the same intention to scam the public again. Bitcoin is decentralized and unique.
However, there are still few potential altcoins that we have seen they are growing their value, but still compared to bitcoin, these altcoins are just duplicates, they or they may not still succeed in the end and reach their peak prices. While bitcoin, which dominates the whole crypto market will always gain a greater advantage, and it actually shows on its current price achievement.
So this isn’t surprising why bitcoin is slowly putting altcoins into their death throne. Or let’s just say, since altcoins have no real utility case and demand, eventually their value will definitely vanish one day.