Social media and the psyche
Every time someone follows me, I get a little excited because in my brain it means that someone else finds me interesting and with enough value to want to be repeatedly exposed to me.
When I post something that gets reblogged, it's like someone's all, "you have made something that I feel is worth sharing and that contributes to human existence. And I want others to be contributed to, too."
When someone likes something I post, I get a little smiley because it means that 1) someone took the time from their life to see what I have to say/do/put out there, and 2) they approve and want me to know.
Net result of all of these things: an interaction (generally positive, no less!) with another living, breathing human being somewhere. Not to mention validation.