What is the psychology of people who like to complain?

People who often like to complain have personality problems and are difficult to get along with. They always stare at other people's shortcomings, are not relaxed at all, lack self-confidence, and have the psychology of comparing with others, for fear that others are better than her and stronger than him. If something goes wrong, I will impose my own faults on others, never review my own mistakes and shortcomings, and I am jealous, narrow-minded, intolerant, selfish, afraid of losing, and love takes advantage of small things. This is the case with a mother-in-law I know. She complains every day that Zhang San is not good and Li Si is not good. She gnashed her teeth at home when she saw that others were rich, but others left her alone, which was a serious hatred for the rich. Narrow-minded, narrow-minded, it is difficult to accommodate people.