Social media is something of a double-edged sword. At its best, social media offers unprecedented opportunities for marginalized people to speak and bring much needed attention to the issues they face. At its worst, social media also offers 'everyone' an unprecedented opportunity to share in collective outrage without reflection.
As far as self-confidence goes, so much of social media is about approval, getting likes, comparing our lives to others' - meanwhile, confidence is an inside job: it's about how you feel about yourself regardless of what anyone else does or thinks. It's a knowing that you're human, you're flawed, and you're awesome in your own way.