So the reason our paper money has value is because we, collectively, including our government, has agreed that it has value. When the government stops backing it for any number of reasons, I guarantee you all of the people will back out of it as well and it's nothing more than wallpaper at that point. The same could happen to Bitcoin because bitcoins value is because we have something that is unique and we have all agreed that it has value. When we stop agreeing that this unique thing can have value then it's nothing more than digital wallpaper.
Secondly, have you considered that a thing's fundamental properties can make it better at functioning as money than other things? Which fundamental properties do you think are important?