Yea the Trump strategy has been disastrous, if you consider trouncing all the other candidates for the nomination to be a disastrous strategy... In which case he is Mr. Disaster..
Goldwater won the GOP nomination. Dukakis also beat “all the other (primary) candidates”. Same for Mondale. What’s your point?
Currently, Hillary is polling for a very easy win against Trump. (and the demographics of 2016 make 1980 comparisons nonsense).