btc is just the value layer, it does not need to be fast or cheap chain. other chains like ethereum will be used for the more complex applications and these chains will interoperate with bitcoin.
True, people debate on these little details and none of them matter, they will be solved one way or another. It's guaranteed that cryptocurrencies are here to stay. Most people don't understand that cryptos in their current form is just the base and when more and more money start building on top of it that's when we will see the real internet 3.0 and all the amazing things you can do with it. It takes some imagination to see what's possible.