in short you never lose unless you sell at a loss
This saying is only said by bagholders who are trying to justify their bad investments. If a coin is only going down, then selling it as soon as possible is the correct action to minimize any future losses. Taking a loss of 10% is a far better option than holding a useless coin in to oblivion.
When BCH was first forked, it was trading at 0.2 BTC. I, and most other smart people, dumped it immediately. If I had held on to it and were planning on selling now, I would have lost 75% of my profits. If I continue to hold for another year, I have no doubt I would lose 95% of my profits.
Selling forks immediately is the only sane thing to do.. when you receive literally "free money", you are at risk by not selling. Thinking that Ver, Craig and Jihan behind it would give the project any leverage against the legacy chain was always seen as a joke. Even if Trump tweeted that he was supporting BCH and it was the real Bitcoin it wouldn't matter, it would still be seen as a joke, and once the president of a big country gets behind a fork and gets defeated, it will add in even more impossibility for any forks to take over (in a way this is what happened already, since many of the forks attempt were probably US government attempting to take over in a non explicit way, because if they supported a fork in a explicit way and got defeated they wouldn't have no cards left).