Why does Obama lie so much?

Actually, he doesn't. You are asking a question based on politics, rather than one based on facts. In politics, it is common to believe one's opponent is a liar, and to accuse him or her of lying-- whether they are lying or not. Thus, this question is difficult to answer, since it asks us to accept that Mr. Obama is a liar. I do not accept this, nor did I accept it when it was asked about President Bush. Politicians exaggerate, and they try to distort their opponent's record to score political points. Whether you and I like this or not, it is part of political communication. And yes, some politicians are more candid than others. But there is no evidence that Mr. Obama "lies" any more than other politicians. In fact, many things he has said are quite accurate and truthful, although his opponents and those who dislike him probably would not accept that.