Why are popular people usually meaner and more judgmental/ less accepting of new friends?

If people are considered popular, how does it make sense that they are ruder in general, more judgmental and less likely to go out of their way to make new friends?

I’ve was in the “popular” crowd at college, but in middle school I was unpopular. The people I knew who were popular were always meaner/ruder and more judgmental and shallow than the unpopular people. Even my friends, who were “popular” were very bitchy. How come some people become popular if they have these undesirable personality traits?
Why are popular people usually meaner and more judgmental/ less accepting of new friends?
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