Love him or hate him, Donald Trump is a prolific abuser of logical fallacies! Most politicians use logical fallacies but there is noone who drops an Ad Hominem harder than Trump.
From Latin, Ad Hominem, is criticising the person’s appearance, character, and personality, rather than the position they are defending.
This is a very extreme case of someone using an Ad Hominem. Tweeting something like this publicly, when you hold the highest office in the land, is not only inflammatory, it’s being a sore winner. If you choose to use an Ad Hominem you will likely create enemies out of people who previously just disagreed with you.