Trump Displays His Cowardice For All To See

Only one president has failed to show for the White House Correspondent's Dinner since Richard Nixon (right before he was forced to resign). That president was Ronald Reagan while he was in the hospital after an assassination attempt -- and he participated by phone from his hospital bed.
That's because all of those presidents had a sense of humor, and they could all take a joke directed at them.
Donald Trump is different. He's a narcissist, and unlike most narcissists, he also has a fragile ego. He simply cannot stand to be criticized -- even in jest for a good cause. He goes bonkers when he's criticized, and he knew the criticism would be strong at the dinner since he basically declared war on the media (for reporting the truth about his continuous lying).
So, instead of trading barbs with the media, as other presidents of both parties have done (to their credit), Trump instead attended a political rally of his supporters in Pennsylvania -- where he could feed his fragile ego.
This makes one thing very clear -- Donald Trump is a COWARD.
(The caricature of Trump above is by DonkeyHotey.)