1. No one believes in bitcoin (because of something).
2. World war.
3. When the power grid/internet has been shutdown.
1. How can you define that if somone or no one do believe on Bitcoin? Hoe can you say that that individual/group may make Bitcoin's value crash?
2. Yea. This Would have a chance make Bitcoin to an end due to but can make bitcoin recover again after the war.
3. It's nearly imposible if they shutdown the internet mate. (It's like you're trying to gamble with 0.00( alots of 0 and 1). Almost everyone relies on internet.