Everyone should fear losing. But we should look it on a broad way evaluating the whole picture than a single instance. It's like winning the battle vs winning the war. Every of us takes small risks and guess work on day to day life. Living risk free is not possible. There could be some loses, temporary or permanent but if you are getting favorable result in long run, you are winning. The win doesn't necessarily be a monetary one. On the other hand even if you win daily gambling but lose your money or even your mental health in long run, you are losing.
By the way, in gambling we can lose not only money, losses can affect our nervous system, when after a loss you feel the consequences of it all day, then this can definitely harm your health, and there are many doctors who say that all our diseases are from nerves, and therefore from stress. So you need to think several times before you start doing something that can affect your health, including money.