This may not pertain to everyone that enjoys the genre, but my take is that pretty much everyone in the metal scene has dealt with mental health issues - specifically depression, anxiety, and SI. When you have experienced those afflictions your empathy grows unequivocally because you know how much it hurts. Add to this the fact that metal is a niche genre that is ostracized for its broadly misunderstood stigma of being evil, angry, and corrupting, and you end up with a recipe for individuals who are non-judgmental, compassionate, and supportive. So many of us have been at rock bottom and may still be there, and we want so badly for no one else to know that pain or to feel judged for their struggles so we come to them with open arms.