The first few bitcoin transactions happened when the government rolled out bond notes correlating well with a reduction in US$ money supply. The black market was paying 90% on a bond note a few weeks later it was 55% on a bond note. Bitcoin is making it easy for these parties in this market to repatriate money. The important consideration is this is usually principle+profits and so the risk vs reward of using bitcoin is at a minimum over ‘getting the money out’. I don’t think there is any problem with this. Will this reduce the need to use the US$ on the black market ? Yes if more people owned bitcoin then they could swap it for goods on this market rather than deal with any fiat transactions. Most of these transactions would be US$10k+-US$150k. Compare buying a bitcoin to the cost of offshoring US$ which is usually about 10% on principle. If you look at the math bitcoin is a good proposition assuming you can sell it on the other side. Bitcoin is useable in Zimbabwe or any other country which has a black/grey market for repatriating money.

Edited for brevity.