Depression
The person who is living with pessimism is most likely experiencing depression. If you don't know what's pessimism, it means to not be optimistic about the future, lack of hope and happiness, which can cause suicidal thoughts. They cause self-negavity and self-harm. If anyone is going through this, please tell a love one or 800-273-8255. It also causes by bully, the internet, false rumors, heart broken, etc.
I hope I've helped! Have a beautiful day!