Interestingly, this does not seem to apply to you if you just HODL and never sell. Also, it's not exactly clear if "fake bitcoin" that some companies offer - where you buy "something" that tracks, say, BTC but there's no real BTC behind it, you can not take custody of any BTC and the only thing you can do is to exchange it back for dollars - qualify as "digital assets". They are certainly not recorded on chain, for example.