Capital gains only arises when you sell and that should not be a problem for someone who wants to comply with tax laws and also there is the option of roll over whereby the money generated from the disposal of the asset that generated the initial capital gain is used to purchased another asset. The capital gain at the time is then rolled forward to the time when the new asset is eventually disposed off. So with this, several options are available based on my understanding of the dynamics of Capital Gains Tax which should not be too different across countries

1. If I kept my bitcoin in my wallet all through 2017 saw a significant increase but I didn't sell, I am not liable to pah CGT because I didn't make any gain.

2. If I sell in 2017 and kept my money, then CGT becomes payable.

3. If I sell in 2017 and I used the proceed to buy more bitcoin when the price crashed, then I will pay my CGT when I eventually sell.

In conclusion, its not about CGT as not everyone in bitcoin lives in one particular jurisdiction to have made such huge effect on price.