That leads me to wonder why they're worried their bank account might be frozen?
Bitcoin's value once collapsed from $1,500 to $100 in two days. That's quite a high risk. Plus it's so volatile that the price can fluctuate by a few dollars each time a coin is sold for cash - which is a similar (or higher) cost than you pay for changing currencies. And $100 in a day shifts happen quite often.
Obviously if you're getting paid in Bitcoin, then it makes sense to use them for what you want. But that huge volatility is very expensive compared to the stability of almost any currency you care to name.