They chose between two candidates chosen via the US presidential primaries. Party members vote for delegates, who vote for a presidential candidate. Republicans chose Trump, then people who voted Republican at the election chose him over the alternative=.
He did not hide his fascist and dictatorial desires and he was open about how he wanted to dismantle the government. When he lost in 2020 he threw a fit and tried to have people do a coup. People did in fact elect him, I can just hope that his actions don't leave too much lasting damage here in Canada. (Maybe de-funding US science will help start to reverse decades of brain drain.)
