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 was initially introduced for a different reason. But with the course of the time, it has taken a different direction. It's more of an investment now rather than anything else. But there are couple of people who likes to spend their bitcoins but for majority it's an investment.
For payments, we have much better options available in the crypto market which are faster and cheaper than bitcoin. But the long term value appreciation bitcoin can provide, it is second to none!