I don't think it's so simple. For one, not all cryptos are equal, and many fall and never recover. So with a coin like this, it's better to sell at some loss than wait for it to devalue completely and lose much more if not everything. If it's Bitcoin, life situations can differ and sometimes a person might need to sell some BTC even at a bad price point due to some unexpected change in financial situation. Also, cryptos are not only about hodling, as some people use it for trading that requires regular buy-sell orders, and some use Bitcoin as money, so they spend it instead of hodling or at lest try to do that.