How would she sell her books otherwise? Coulter is like Howard Stern or Don Rickles. Being reasoned and rational wouldn't sell book one. She can't carry on a calm debate or any other discourse without personal attacks, her fans wouldn't believe her if she tried. She's an act, like Michael Moore is an act. And a very good one at that. Both of them make a ton of money off the personae that they adopt.
Be that as it may. You prefer to attach the messenger over the message. While the messenger can have any manner of motives, its the facts expressed, regardless the messenger, that one finds meaningful.
Not completely disagreeing that much of what people do is for self interest. However the question is: does what they do help or hinder the agenda. Despite going over the top many times Coulter, in my opinion, undoubtedly furthers the conservative agenda. People who do not follow politics, like Freepers and other news junkies, know who she is and what she stands for. If it weren't for people like Coulter, most lib icons, like Shrillary, would go unchallenged.
It's better to have some apolitical people being dismayed by Coulter's MO but having doubts raised about their glorious lib leaders than not knowing who she is and swallowing whole all the liberal crap that swamps them every day of the week. In short we still need activists who get the message out...even if they are only out for themselves...which I personally do not think is Coulter's only motivation.