Whelp, not sure if this is all accurate and updated, but Wikipedia gives a whole lot information about many countries.

https://en.wikipedia.org/wiki/Capital_gains_tax

For my country, the Netherlands, it says:

Capital gains generally are exempt from tax. However, exceptions apply to the following assets: • Capital gains realised on the disposal of business assets (including real estate) and on the disposal of other assets that qualify as income from independently performed activities • Capital gains on liquidation of a company • Capital gains derived from the sale of a substantial interest in a company (that is, 5% of the issued share capital)

However, you start paying wealth tax if your total amount of currency + assets exceed 20,000 euros. But yeah, good luck enforcing that law with crypto. I suspect the only way they can know is when you cash out for fiat. On the other hand, there's a 4 year prison sentences for not filing your taxes :/