The best case scenario for bitcoin is it becoming the de facto monetary standard, meaning there would be no reason to buy or cash out, as everything would be priced in bitcoin.
> as it is inherently flawed: price fluctuate too much, and favor early owner of it.
These aren't flaws, welcome to economics, man. Once bitcoin gains enough things will be priced in BTC, so fluctuation won't be an issue.
Deflationary economics benefit the savers, while inflationary economics benefit the spenders. Just because bitcoin's economic model isn't something you're used to or like doesn't mean it is 'inherently flawed'.
It is flawed because the pool of currency is limited. What happen when our economy grows fast, but then there's not enough BTC to support it? Price will decrease and benefit the savers, sure. But then many people will prefer to save instead of spending, which will not fuel the economy
Bitcoin will never replace current fiat money as it is inherently flawed: price fluctuate too much, and favor early owner of it.