Lack of self-confidence can really ruin a kid’s life. In fact it’s the same for adults too. Martial Arts are great at instilling self self confidence because they give a person the ability to control their environment far more, and they realize that they don’t have to be the effect of a bad situation.
There are a couple of types of bullies around. There’s definitely a small proportion of the population, who are out to get you, whether they are trained in Martial Arts or not. But they are less likely to bully a kid if it looks like they are confident and willing to fight back. The other type of bully is also lacking in confidence,and it can actually be a great thing for them to get trained in a Martial Art too, because boosting their confidence reduces their need to bully other kids.
There’s a post about this worth reading at thesweetscience.tamnguyenweb.com