As with most countries/jurisdictions who try to prevent use of Bitcoin, they claim it’s due to volatility (consumer protection) or use in criminal activity (money laundering/fraud/drugs/etc).

Truth is that the volatility is a short term phenomenon, and cash is much more widely used (and effective) with regard to financing crime.

Bitcoins offers its users a new kind of control and autonomy, not just over their financial technology but a choice to not use their own government’s currency. And governments hate that. It’s “new and scary” to those who have benefitted from the existing system. Easiest way to prevent your power from being upset is to ban the competition.