Well at this time obviously there are many who are entering a currency called "shiba" and there is a lot of FOMO there, as long as there is a bullish trend of BTC this may occur and stay up, but at the moment that BTC makes a correction, These coins will fall a lot, for me meme coins are special for those who hunt the pump and dump, and I agree as you affirm, that according to PlanB this year it will reach $ 100k.
This is normal to cryptocurrencies, they all follow bitcoin price, just like you said, it will be a more big blow on altcoins if the price of bitcoin is falling, even to the extent that altcoins will fall more than bitcoin. Only that what happened to Shiba Inu recently was surprised me, when bitcoin was at $67000 when it reached ATH recently, Shiba was around $0.000004, but when bitcoin was dropping, many other coins followed as usual but Shiba continue to increase and reached $0.0000089. But th the coin has decreased now and it is presently below $0.000006, while not mean it will not follow bitcoin price again.