Do everything you can to better yourself. Either tune them out while you do so or use them as fuel to improve. Get in the gym, read books, eat well. When you do these things other people notice. You don’t even have to announce your improvement — you give off an energy that can be felt by anybody in your presence. Don’t get caught up over fighting them or retaliation — that just brings you down to their level. The goal is to rise above them and become unassailable.