Had Hillary Clinton become president, many people would never have accepted the fact that Donald Trump would have been the single-most corrupt, incompetent, unstable, unqualified person ever to hold the office. Many of us always believed that would be true; others (though increasingly few) will never believe it.  But many who did not know it, or who crossed their fingers and hoped for the best, now realize what a tragic mistake they made in ignoring the evidence that was readily available. 
The only good that I can see coming from this tragic presidency is the possibility that, going forward, more people will take seriously the advice of Maya Angelou: "When someone tells you who they are, believe them the first time." There is nothing we know now about Donald Trump's defects of character, personality and judgment that we did not know before he was elected.