So when people move from bitcoin to fiat in an exchange and transfer to their banks they likely have to pay capital gains tax since there is nowhere to hide at that point. Does it make it more likely they just buy back into bitcoin again in one of the dodgy exchanges which the tax man would have a hard time policing?
If your windfall is huge enough, you can move to a jurisdiction where capital gains tax is zero (there are plenty like that).
You can stay with Bitcoin and try to spend it. If not, you can move to off-exchange transactions and try to convert your bitcoins to fiat.