It's not normal at all. If you lose and feel sad about it, you've invested more than you should have. It should be a learning moment, and not something that puts you down mentally. It's not gambling where when you lose, you directly think about winning it back, which more often than not will work against you. In some cases people try too hard to make their investments or trades successful, where they keep on losing and losing. It's a classic form of capital destruction that you'll start to notice when it's too late. That's why when you keep on losing without any improvement in sight, you should understand that it's time for you to take distance from investing/trading.