I see people paying USD 10 for an item, and then paying USD 30 in fee for the BTC transaction, and I realize that this is not sustainable. And its impossible for BTC to become a mainstream payment method if the price is increased with x3 when you buy something.
Where did you see that? I have never ever paid 30 USD in fees on transactions with 1 input 2 output or 2 input 2 output. If you are going to send $0.5 to 20 users, then you'll have to pay $30 in fees but in the situation that you describe, there is no way someone had to pay $30 in fees in this year.
(....)
This is a very rare case, where the transaction fee could end up high like this especially before, the bull market, where the price of Bitcoin is at its peak, and multiple all-time highs were created, that's the time that I can recall that this kind of high transaction fee happened.
I can feel what OP is saying here, Bitcoin for this kind of payments is not that really good, but I believe there will be more technology will come to solve this issue of Bitcoin.