I have watched a YouTube video recently from Ryan Berkness in which he explains how taxation on cryptocurrency works in the US.
Basically, the only way for cryptocurrencies to be taxed in the US is if they become spendable. Before that, these are not considered "realized gains".
Plus you are only taxed on the profit you've made after the currency was transferred into a spendable state. This is most likely why many countries are now looking to make Bitcoin an official payment method, since it would immediately become spendable.
I'm new to this platform, and I'm not sure if it's ok to post the link in here. Just in case it's frowned upon or not ok, Please feel free to delete this comment.