2) Govenrment might ban Bitcoin in their country
3) Panic selling might happen
4) Bubble price might pop and lead do big drop of price
5) Price ceiling might hit which then price will only go down.
6) Hackers or just being neglectful and loosing your account
7) Bitcoin might be used for illegal activities and might push the prohibitation or freeze the trading of Bitcoins.
2) Payment processors are international, so if your country ban Bitcoin, you could use exchanges outside your country.
3) Panic selling will not cause any significant price drop.
4) There is no bubble when you have a limited supply.
5) There is no price ceiling for Bitcoin.
6) You could also get ass jumped or lose your car key.
7) Bitcoin like any other currency, I don't see them freezing other currency trading.