Martial Arts have are rooted in self-defense. The first line of self-defense is to avoid physical conflict. If physical conflict cannot be avoided then one must be able to defend themselves and their loved ones.
In general, non-competition training, there is very low risk for serious or permanent injury. Experienced training partners understand body mechanics and exercise extreme control in sparring sessions.
However, if your goal is to compete at any level, there is an increased risk for injury that comes from an increased level of intensity associated with competition.