but isn't bitcoin is currency so 1 btc will be always 1 btc, unfortunately we don't look in that way, we just want fiat currency so we calculate profit and loss in fiat currency only. so bitcoin became an investment for many
One thing is very important, when the price is going down, you will not lose anything. You just need to make sure you don't sell your coins. As long as you don't sell them, you won't lose anything. It may feel like you are losing, but it's not the case.
you have a point though, if you dont sell your bitcoin you would not suffer such loss because you didnt exchange it to fiat. As long as you hold it you wont suffer lose in any way and also we could wait as long as we want and we have the will on when we would sell our bitcoin as we see that the price is profitable enough to sell our coins.