- Too many people on the internet who just want it to be about them. Me Me Me. Look at me. I try not to be that guy but I am sure I have been there too. Look at facebook. It is mostly a bunch of family/friends showing their latest vacation pics, or their kids doing some stuff (guilty as charged here) or whatever. It is mostly about THEM. Look at me. Me me me. Instagram. Need I say anything ? Twitter: A bunch of people who have opinions and if they are famous, everyone listens in. Like ok, who cares but people do. When someone "less fortunate" sees all that stuff, they get depressed/jealous/sad whatever. Why can't I have those things ? Why can't I go to that great vacation ? Oh, look at THAT family. How perfect they are. My life sucks.

- People are really becoming too reserved and within their own circles. Internet has made it much easier contrary to what we may have thought when internet started. Now you don't need to worry about socializing or getting to know your neighbor. You can literally get/do anything online these days which also means you create your own echo chambers. For example, why participate in a debate with a fellow neighbor/friend when I can go on reddit (anonymized) and write whatever I want for the most part. I was talking to someone few days ago and they mentioned "We used to almost know everyone in my neighborhood 15 years ago and now in the same neighborhood, I only know a handful"

I wouldn't say most commenters online are depressed. I think it is more because of how our society has become.