2) You're some kind of New Media Guru, and your tweets consist almost entirely of either you replying to one of your two-million other followers saying "Thanks for the follow!" or "10 ways to gain 50,000 followers for cheap!". I don't _need_ followers, that's not why I'm on Twitter*.
3) You're not a real person, but a bot, tweeting carefully calculated items designed to pull people in so that they see the adverts which make up 10% of your tweets.
Basically, I'm interested in people, talking either about topics I find interesting, or their lives (which I find interesting either because they're my friends or because they're interesting people). I am not interested in advertising, marketing, or anything else which has the sole purpose of trying to make me do something.
This post brought to you by me losing count of the number of authors who have added me, in a vain attempt to have me buy their book.
*I'm on Twitter because I dump my links there, and people reply to them sometimes, to tell me when they're wrong. Also, people post interesting things, and occasionally have interesting conversation. It's one of my least favourite social networks, but the occasional awesome thing I find on there makes it worth putting up with how awful it is trying to have a discussion there.
Original post on Dreamwidth - there are comments there.