I can categorically state that I cyber-stalk for one of a few reasons. The first and most likely is that I feel some sort of emotional connection to a person, coupled with a feeling of inferiority, and I want to take part in their life without revealing the sad, shameful drudgery of my own. Don't get me wrong--I'm not saying my life is merely sad, shameful drudgery, or even that it contains much of same--but that's how I feel in comparison to the person I'm stalking. If I haven't put someone on at least a moderately high pedestal, I'm probably not stalking them.
Unless... they've done something to really tick me off, and I have no way to get back at them. Then, the second reason I might stalk someone comes into play: a rancid, bile-spewing loathing of them, and all they stand for. Let me be clear; I can't recall the last time I exacted vengeance upon someone, but even knowing that I could is usually enough to dispel the raging ball of fury burning in my stomach/oesophagus. If I have no clear avenue of revenge, I'll stalk them, reading their stupid comments on Facebook (or Protagonize) and virtually eavesdropping on their idiotic conversations with ass-licking sycophants and just generally fuming at them from afar, until a) I have a conversation with my mother, and her various helpful sayings ("hating someone is like drinking poison and waiting for the other person to die") or b) I share some of what's happened with someone else, and they agree with my assessment of what a tool the other party is, or c) I get to know them a bit better, and realize they're not so bad after all, and forgive them because that's the way I was raised. More rarely, I just get over it eventually, because really, holding onto a grudge for months or years is borderline psychotic... and even *I* occasionally worry that I might be going too far.
Finally, the other primary reason I might be stalking someone--and I'm not sure this even counts as stalking--is that I live 6 Timezones ahead of 99% of my friends and family. When I get up in the morning, and it's 8 a.m. in England, and my kids are still asleep (touch wood) and I log into Facebook, my siblings (the halves and the wholes) and my parents (the steps and the naturals) and my friends (the old and the newer) aren't awake; but they've usually left 3 pages worth of highlights from the night before, right there on their Walls. I read conversations between my sister Julie and her best friends (they used to be my friends, too) and I read conversations between old friends of mine and their families (I used to practically live with Miss Linda and her kids, some summers) and I check up on birthdays and real-life get-togethers and outings and road trips and such-like that I will probably never get the chance to participate in, ever again.
Faced with the sheer hopelessness of maintaining my relationships with all these people, these wonderful, unique, fascinating people, whose lives I'm no longer really a part of, and whose small world is so far away from my own that the two barely intersect anymore, I don't leave a note or a comment. I don't say hi, or ask how anyone's doing, or share details of my life. What's the point? If there's a reason (a birthday, a prayer request, a need for factual information that I happen to have) I'll chime in briefly before disappearing; but usually, I just disappear. And surely, that's the very core of what stalking is; memorizing someone else's life, without sharing any of your own. By my reckoning, I'm one of the worst (best?) stalkers I've ever met (although, really, how would I know?) and for the most part, I think I understand why I do it. I think the underlying reason could be summed up as 'loneliness', or 'loneliness with a light sprinkling of terror'--and I doubt many people would give a very different answer, if pressed.