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.
Well, it’s an indicator for where majority of the market lies, but that’s not for all the coins in the market, there are still a lot of coins that don’t rely or correlates with bitcoin’s price at all. So, if you’re going to be thinking that every of the coins in the market would go up when bitcoin goes up, then I am sorry to say that you would be wrong by thinking that such is how it is in the market.
Bitcoin is still being used as a method of payment till this day, and is still preferred more than other coins there is in the market. No matter how things might seem to you today, maybe because of the fees, yes I do know that, but it still beats others in usage rate. The stablecoins you are talking about are nowhere near when we talk of usage rate, you’d hardly see them being accepted by anyone.