Why I don't believe that Bitcoin could go to zero is twofold.
Bitcoin is not a business, it therefore cannot go bankrupt. A stock can go to zero because a worthless business can easily cease to exist but Bitcoin cannot easily cease to exist. Entire mines in China were flooded knocking out millions of dollars worth of equipment and yet, the money on the block chain remains intact and safe.
Bitcoin architecture is massive and valuable with each added node it's value, redundancy, speed, and reliability increases. It's value is therefore in the size of the network and the block chain that feeds it.
Just food for thought next time some moron says that Bitcoin could go to zero, maybe he didn't think that through all of the way.