Btc main use case now is this:
Bitcoin is good market prices indicator to show just wich way all other coins likely will go.
If there is another reasons to use ....its unlikely.
People say specially traders that btc price is good indicator also to show wich way altcoins might go.
For payments and moving funds the stablecoins are definately best ones.
But yeah..now we know btc main usecase
Bitcoin is a currency and store of value. I don't really believe that the main use of bitcoin nowadays is intended as an indicator of price movement in the market only. It could be an indicator but that is not its main usage. In addition, not all coins actually move alongside the bitcoin's price. Hence, it wouldn't be accurate to claim that. Although it would work for the majority of the coin, but not for all because some coins still go against the flow of the current market just like now wherein some coins continue to pump despite the downhill trend of bitcoin.
One must still equip himself with proper knowledge regarding technical analysis to know which coin is best to invest in right now that we have a bearish market and which one is not worth it to risk.