Why is it that in almost every instance presidents have taken a stand, but the truth has always been the opposite?

President Bush took a stand claiming Iraq had a stockpile of WMD, when this proved wrong, Bush claimed that the stockpile of WMD was flushed down the Tigris and Euphrates, which was never evidenced. Later; the President was questioned about his source of information about the WMD in Iraq, to which he replied his Intelligence agencies got the information from allies and the ally got it from an African informant. Is this a good reason to wage war against a sovereign state, whether that state is a dictatorship? I am not against the riddance of Saddam, but I am against the tale that put troops in harm's way.

The sitting President claimed he had nothing to do with rigging the 2016 elections, but now there appears to be evidence to the contrary; why lie? When there was doubt that the election was rigged then, why not correct the issue and redo the election, regardless of whether the Opposition Candidate gave up or not; why not clear the doubt? I am only vouching for fair and unbiased information and, I don't care which candidate wins or loses a fair election.