That argument is usually used by gamblers investors. Even if you don't sell, what matters is how much that bitcoins are worth now when you need to spend them compared when you bought. So if you bought higher you are losing money a suboptimal investor, like everyone else. The past is over and you don't know what will happen in the future, the only thing that counts is the present what happens in the future, and how well your choices have prepared you for it.

Technically not selling is the same than buying not buying...