Privacy, not having to share your personal information is a good reason. However, the vast majority of people don't care about sharing their personal information while making most of their transactions.
You don't have privacy though. Unless you're doing an in-person transaction you don't have total privacy when it comes to the "real" to bitcoin transaction, or visa versa, and your bitcoins are entirely traceable to the point where if someone knows info from a single (unwashed) transaction, they can trace it back to pretty much every transaction you've made with an address and even in some cases other addresses you use. That also makes buying real world products with bitcoin high risk, since any shipped product still requires real world information which is stored on a server which could be hacked which would tie every transaction you made/make to your real world details.
many people think that in a few decades governments will crumble and every single person of the 7 billion people in the world will be using bitcoin. this is just not the case.
People have been saying the same thing about gold and silver for quite some time. Who knows, it may happen at some point, but in the meantime the diehards didn't sell when it went up and they won't sell until they really have to personally (at which point the price will well below it's peak) or until not just the dollar but most viable alternatives (if the dollar collapsed we'd probably switch to the Canadian Dollar before gold as an acceptable currency) stopped working, at which point they'll have a head start on everyone else but it won't really matter since society will have pretty much collapsed anyway making the majority people who are poor, starving, and don't have precious metals to trade.
no one should be worrying about volitility. as there are services such as bitpay that will give instant valuations and a good enough time buffer for customers to pay wthout the merchant losing out. and then when bitcoin has 'sowed his wild oates' so to speak and calmed its volitility down then you will see the future of bitcoin.
Volatility is actively preventing adoption of bitcoin, both because it hurts its real usability and because of the PR effect, mainly nobody except for techno-geeks and crazy people are going to buy into a currency that drops 46% in a day. Also, merchants aren't going to accept a currency that changes so much as to risk rapidly devaluing any sale that they make below their costs which is why many of the merchants that currently accept bitcoin are places like Amagi which deals in metals, or mining companies, which are speculating in their own way on the adoption of bitcoin.