A better analogy is stocks vs Real Estate. Let’s say you buy a home for 200k, and sell it later for 300k. Every day in between, when you “weren’t in the market”, the potential value of your home fluctuated: it’s entirely possible that halfway in between, the top bid on that day, were it listed on the market, would have been for 6$.

Of course in reality you don’t see all these intermediate hypothetical prices, but in theory they’re there just the same as if you bought stocks and then didn’t look at prices for 10 years.

The fact that there is a price on the open market (the fluctuation of which determines your unrealized gain/loss) does not obligate you to sell at any particular moment: that’s just like owning a home and not caring how much someone would pay for it on Tuesday vs Wednesday because you don’t intend to sell it in the first place.