I spoke to an accountant friend of mine (this should not be considered tax advice, get your own accountant and pay them for theirs), and she told me that any time you either exchange for another good (like another crypto or something off Amazon) or for government fiat, you have to claim any capital gains at that time. It will get very complex very quickly if you have a lot of churn. Yes, the IRS really expects you to do this. On what level they decide to enforce this is anyone's guess.