I'm not sure that would cause the bottom to fall out of the dollar. c.f. http://www.economist.com/node/21551492

If people had to carry around a wheelbarrow full of U.S. dollars to pay for something, I would consider that to be "the bottom falling out".

I realize I am throwing myself in the fire by offering up the whitehouse/nuke scenario. However, nobody has proposed a reason as to why the value could fall out from under Bitcoin completely tomorrow which I assume would be an equally unplausible scenario as a nuke hitting the whitehouse.

I bought into BTC when it was $30. It fell to $1 very shortly thereafter. It can happen.

I'm still long on BTC, but please have no illusions. Don't put anything in that you can't afford to lose.

I think you misinterpreted the image. It's currency traders with a pile of currency on a table.

Somali currency is not worth much, but it was never worth much. What is interesting is that the government basically going away did not lead to worthless currency.

The bottom would fall out of bitcoin if X% of the users decided they didn't want to use bitcoin anymore. If that's the same X% as the dollar, that's far fewer people, and thus correspondingly more likely.