When explaining bitcoins advantages over cash to someone else, there are a few things that come to mind:
1. They cannot be counterfeited
2. Can be sent anywhere in the world with no (or very very low) fees
3. Mining fees dont go to big banks
4. Low transaction fees, coinbase estimated bitcoin could reduce payment processing fees worldwide from $500 billion to $50 billion, so 1/10th of current level
Any other to add to the list?
5. The value of bitcoin will increase(deflate) over time as opposite to cash(inflate).
6. The value of Bitcoin is volatile and although you may go to the store with $100, by the time you get there you might only have $80
Indeed, It's a big problem and that's why people can trust bitcoin when buying something more expensive, But we can see this as an advantage for buying/selling for profit. The unstable price can make huge profit great example last 3 days when bitcoin went up about $80 and that's a huge profit If you have a pile of bitcoins.
While it is great for the profit building (I agree on this), that is a big thing that holds it back from being usable as a currency. If someone wants to break away from the banks/financial system and only use Bitcoin, they will never know how much money they have. If I have $500 sitting here and bread is $1 a loaf, I can go to the store in a week and (assuming prices haven't gone up, which is not likely to happen in a short period) know I can buy 500 loaves of bread. Conversely, if I have a Bitcoin that is worth $500 right now, I can go to the store and within a minute be able to afford only 450 loaves or maybe even 580 loaves. This is a huge problem.