Some people try to build themselves up by speaking against others. They believe that talking about the faults and limitations of others makes themselves seem better and more elevated than those people.
It is a total illusion to think that you are actually building yourself up when you put others down. Speaking against other people is a violation of the Torah commandment to refrain from speaking lashon hara (negative speech). Someone who speaks against others without a practical and constructive purpose is lowering himself by doing so.
Every time you control what you say and don't speak against others, you become a higher and more elevated person.
(From Rabbi Zelig Pliskin's book: "Building Your Self- image and the Self-image of Others" (Artscroll) Chapter 61)