While Donald Trump's lies at first cause a stir and sensationalism, in the end they only hurt him as fact checkers uncover the truth and it eventually comes out. Anyone who puts a little effort into investigating his comments will soon discover that most of what Donald Trump says is false and has no substance.
Donald Trump's lies continue to haunt him. While he was able to get away with it in the Republican primary, he is now under greater scrutiny. Each time he lies, such as bragging about endorsements that never happened, he looks foolish and turns off voters. This helps explain his sinking poll numbers.
Yes, his lies hurt him more than they help him because it is too easy to prove he is lying. Once everyone knows he is lying, it becomes difficult for people to trust anything he says. Who knows if he is ever telling the truth? He is a true pathological liar.
Donald Trump is running for president, and as a presidential candidate everything he says and does gets put under a microscope. Although you might think that lies wouldn't hurt Trump too much with Clinton being one of the least trustworthy candidates to ever run, everything that can be used as negative press against Trump, gets used.