Don’t look at the price of your altcoin in fiat, look at its BTC price.
Most alts don't trade directly with USD or € or whatever currency you live in, they trade in BTC.
It means that if you bought an altcoin because you think it's better than Bitcoin and the altcoin price stay constant when bitcoin moves up, it means people are selling them against BTC.
So either your did you own research bad and the altcoin wasn't really better or it's time to buy the dip.
A few Alts have broken their previous ATH in fiat (Ethereum and Cardano for exemple) but are very very far from their bitcoin ATH, and those projects aren't shitcoins vaporware but real projects making big stride forward to be better than Bitcoin.
What does that tell us? It tells us that a lot of Alts are currently undervalued. And what should you do when something is undervalued? Yep you should buy, altseason is real and it's coming.
Just remember that during bear season, Alts are the one taking it hard and making bitcoin crashes look like child play.
This is financial advice… I'm just not liable for your loss girls and boys!