But will bitcoin ever succeed at being used as a stable currency? I've been told many times that when bitcoin matures to the point that everyone knows about bitcoin and owns some the price will stabilize and it can serve as a currency that is stable...
I think this is actually your question, the issue of stability, and not if Bitcoin is a currency, which we already know it is cause it's already used in the same way different currencies are used all over the world, processing buying and selling/payment for services. Imo, It'll take quite a long time for Bitcoin to attain stability, if it ever will; but I don't think it's going to be as stable as Fiat that you use daily, and I don't even want it to be, Bitcoin is an anti-inflationary currency and it's somewhat easy to evaluate its value either when it's appreciating in price or losing value.
Having said that, $100 I know is $100, but the value never remains the same, inflation reduces/ devalues it's purchasing power without changing the paper note, but the truth is $100 today in a few years time could actually be half it's value in terms of what it can purchase, that's not stability for me, it's actually a misconception if you ask me, Bitcoin may not be stable, but you actually know it's worth at Everytime cause 1Btc is 1Btc.