Yes, like some other people wrote, the risk of being hacked is not very high if you keep your bitcoins safe. If you keep them in cold-storage, I would be willing to say that it is almost safer than keeping USD in a bank. Or if you keep it a place like Coinbase who is insuring your funds. They keep less than 2% of customers funds online.
In regards to fluctuations, yes you are right. Bitcoin is more volatile that usd or event stocks. But I would still keep some percentage of my money in BTC at all times. This can also be seen as a hedge agains the inflation in dollars.