Foolish? No. Uninformed? Yes.
Trump's transgressions, crimes, lies and misdeeds were extensively well-documented long before he ever became a politician, long before he ever vomited forth the birther conspiracy, long before he became BFFs with Hannity and Fox News. The only reason a person would have voted for Trump despite all this information being out there is 1) Because they put party before principle and willfully ignored his misgivings simply because he's Republican, or 2) They simply didn't know all those bad things about him, which means they voted despite being uninformed.
I prefer to give people the benefit of the doubt and go on the assumption that they were simply uninformed on Trump's notorious misdeeds, not because they willfully chose to ignore those misdeeds for the sake of putting someone from their own party in the White House. Because to believe the latter would be to acknowledge that people are, by and large, utter ******* morons. My advice: Next time you vote, make sure you do your homework on the candidates first and actually vote for someone who actually cares for America, not someone who only says they do while robbing it blind.