BE HONEST: Who here would have believed last year that Bitcoin would be near 18,700 today ?? Everyone knows darn well that anyone correctly predicting such a price drop in bitcoin would have been ridiculed here in this forum. So stop the self delusion for a minute and consider that Bitcoin could still go FAR LOWER...
I think no one believes that because what we see last year is only a bull run. We know that bull run can't last forever but we only assume that the fall is not going to be hard than what we are currently seeing now. No one can accurately predict the price of bitcoin and if ever there are predictions who are close to it then I think it was only a co-incident.
My answer to your question would be is; I will never lose my faith in bitcoins no matter what happens. Selling at a loss is I think not a loss of faith in btc as long as they can re-buy again later on. That is only one of the strategies that mainly used by the traders. Never tried that since I am only an investor but I just hodl and buy more once the price dumps.