A constant refrain from those heavily invested in the financial system is that governments will "make Bitcoin illegal."
What's missing from this perspective is the possibility that as Bitcoin becomes more widely-recognized and doesn't vaporize in a puff of schadenfreude, it gains powerful supporters who can ensure that the clampdown never happens.
Ironically, there are those using Bitcoin who would like to see nothing less than a total ban of Bitcoin use in the US. They see this as final proof of the utility, value proposition, and when the ban fails to work, vindication.