Potential attack against #Bitcoin (I think?): governments decide that the coins they confiscate will be sent to an address whose private key is deliberately lost. Then all #Bitcoin they confiscate will be lost.

Now, that could make everyone else's coins more valuable as there is less in the circulating supply now, but there is a chance that Governments are able to confiscate all 21 million (or close to it) and render #Bitcoin useless.