In fact, it usually happens that all cryptocurrencies become cheaper along with Bitcoin and become more expensive together. Yes, there are coins that can rise in price regardless of the change in the price of Bitcoin, but it is basically some little-known coins that someone pumping for the sake of temporary profits, after which they can become cheaper even if all other coins go up. It happens of course that regardless of Bitcoin prices for some altcoin are growing due to positive news from the #DevelopmentTeam of a certain coin, for example, the expected updates, the addition of a coin to large exchanges, etc. Therefore, for a more accurate answer to your question, you need to consider each particular coin separately, and not all at once.