> assuming the price will ever recover to the same levels you bought in at
No, what I said doesn't assume anything. It's plain English and logic.
If you want 1 Bitcoin for $1000, you lose $1000 and gain 1 Bitcoin when you buy.
If you don't sell the 1 Bitcoin, the changes in the market don't magically take away your 1 Bitcoin.
If you sell that 1 Bitcoin for $2000, you have lost 100% of your Bitcoin.
If you want to talk about opportunity costs, compare it to a vacation that costs you $1000 and 180 hours of your time. Can you later sell that vacation for $500, or get back any of your lost time? No, but if you sell your 1 Bitcoin for $500, then you're $500 richer than if you had spent that $1000 on a vacation.