Donald Trump is a bad loser. Yet, he should be well used to it. Lost elections, bankrupt companies, including a casino business where Trump filed for bankruptcy 4 times, failed marriages, not getting his longed-for Nobel Peace Prize, caught fiddling cancer charity funds, all the lawsuits he has lost or had to settle out of court, his failed University... I could keep going.
The idea that he is a winner, knows all about business and is an expert on every subject, is for the birds.