1 If the bitcoin becomes a bubble and burst. This will be linked to the flash crash but this time that looks impossible.
2 If the exchange site will be banned in the various country because of the exchange site as a centra key in the bitcoin or crypto.
3 Too many hackers, scammers in the crypto.

A lot of the things that makes me fear about the bitcoin itself. But the politic and regulatory seems to be a serious thing rather than other.