From my experience, people cause a change in self-esteem , but on the internet you meet others from anywhere in the world. These people usually try their best to be nice, and if they aren't, just leave, they don't stay around. The internet is new beginnings, new chances to make friends. Let's be honest here, friends raise your self-esteem. Being around people who like you makes you happy. Being happier can raise your self-esteem. As a small bonus, these people that are met usually have similar interests because people are met through others looking for the same things.
Just because you are able to confidently communicate with others online, it doesn't mean that your self-esteem has overall improved. Online settings and face to face social settings are immensely different situations and hence call on different skills. Many often feel more apprehensive about participating in social settings because there are more people (some whom we've never met before), and conversations are paced dramatically faster. Without the protection of a computer screen to hide real (and possibly offensive) reactions and the comfort of knowing we can retract a message that could potentially hurt another person, our self-esteem may in fact deteriorate.
Most people only put what they believe is the best of themselves out onto social media sites. As a result, their profiles reflect a view of them that may best be described as "having rose-colored glasses on."
In other words, when you view someone's social media profile, you're seeing the greatest things about them. You see the wonderful vacation photos, the news of their engagement or new baby, the promotion they got at work or new job, their brand new car or house, etc. If that same person were to lose their job and be unable to pay for the vacation, the car, or the house, you probably wouldn't see it on their profile.
By viewing these profiles, people sometimes make the mistake of thinking the lives other people lead are somehow better than their own. It's easy to do this when all you see is the best of what happens to others and compare it (unfairly) to what you know happens in your WHOLE life.
In my personal experience and from what I understand social media primarily inflicts harm. Of course God shares a huge part of the blame for this harm because of the ridiculously poor quality of the world. I believe God should be blamed when he has an obvious hand in the ridiculously poor state of the world!