Self esteem certainly isn’t everything, but I do believe that people who truly accept themselves are more likely to be kind to others. (Does anybody truly and completely accept oneself, is another question).
When you are brimming with complexes, you use as many coping mechanisms as you can to try to ease and soothe yourself.
You might act like you are better than others, be aggressive, be submissive, be a ‘people pleaser’ or a doormat.. whatever decreases your own feeling of inadequacy, and makes you feel better at least for awhile.
Believing you are better than others is also just a coping mechanism for underlying feeling of lack of self-worth.
Need for power most polititians demonstrate, in my opinion, is a textbook example of lack of self esteem, masked behind the ‘I am God’ attitude.