You take that risk when you leave anonymous currency on a public network. Regular banks are also hacked all the time but are insured by higher taxes and fees. It's always a tradeoff of privacy, freedom, stability and security. No currency is perfect
I have two words for you, "Bull" and "Shit"
From Mt Gox Bitcoin Exchange press release
Non-technical Explanation:
A bug in the bitcoin software makes it possible for someone to use the Bitcoin network to alter transaction details to make it seem like a sending of bitcoins to a bitcoin wallet did not occur when in fact it did occur. Since the transaction appears as if it has not proceeded correctly, the bitcoins may be resent. MtGox is working with the Bitcoin core development team and others to mitigate this issue.
You should probably not try to BS your way through a subject on the internet. If you do GOOGLE is not your friend.