I don't fully understand how NFT losses are treated (i.e. do you get a capital loss?) but the issue is with timing. THe tax man is not going to wait until you possibly convert to their currency to collect taxes; the gains and losses get attributed to the year when the transaction occurred. The high volatility in the investment is what makes the crazy swings possible - but this risk really should be priced into the expected return. I wouldn't be surprised if NFT gains are treated more like lottery winnings (in many jurisidictions); it's taxed at payout against the current year situation, regardless of what you do with it.