wow! can't believe the voting thing at that age.
My kids have had some rough stuff with self esteem and how others view them.
I tell them the good things about themselves and get them to repeat it ie- I am good at making people laugh, I am funny.
I also will ask them randomly to tell me 3 good things about thems- or 3 things they like about themselves (not always the same)
Good luck. This is a hard area for parents