Bitcoin is still very risky though, but I wouldn't sell all of them ^^
Neither the dollar nor the euro are going anywhere. They may/will fluctuate in value, but they're certainly not going anywhere. Notably unlike Bitcoin, they actually have something backing their value: Giant armies that will ensure that any land within their jurisdiction has its property taxes paid in fiat, and the ability to insist on paying all their government's expenses (which are huge, obviously) in fiat currency.
All fiat monies eventually fail. All of them. It's human nature... eventually TPTB succumb to the temptation to endlessly produce more money, and that's a situation that is unsustainable in the long-term. Nations can force people to use their currency... they can't force people to actually value it. Now, whether they'll fail tomorrow, or fail in 100 years is another issue.
But just like gold, Bitcoin's backing is both its monetary usefulness and its inherent utility. It allows me to send the world's first ever decentralized, pseudonymous virtual asset to anyone, anywhere, in seconds; that alone has enough power to make national governments quake and (dumbly) attack it. Yet even if it's monetary usefulness somehow disappeared, the technology itself still has numerous other uses (demonstrated in part by the proposals based on it, including Namecoin, which actually exists and works.)