I often lose my temper when altcoins drop sharply.
And in general, I sell altscoin at the bottom
You should try to control your emotions if you want to be a successful trader. Altcoins dropping is not always bad. You should see it as an opportunity to buy more of that good altcoins. The more you have when it drops, the more profit you will take when the price recovers. But this is only true if you are holding a good coin, not a pump and dump sh*t coin.