Scars are the mark of strong person, they represent the endurance and strength you needed in order to withstand the physical or emotional abuse. That thing or person which tried to kill or weaken you, contrarily only made you stronger.
And piercings and any other decoration you find pleasing to yourself. It also applies to what you eat/hoe much you weigh. Fuck anyone who tries to tell you what to do or how to live your life based on their values