We will likely never know the details, beyond what his niece describes in her book, but it seems clear that Donald Trump never learned what most competent adults learn at roughly age two or three — you don’t always get what you want. As the spoiled child of a rich father, he grew up expecting always to get what he wants, more or less immediately.
To some extent, we can say that this rule is just the rule that the Buddha taught us. Life is full of disappointments. Somehow, Trump missed this rule. We can regard Trump as a cautionary example of why we should meditate. The Buddha also taught that the only viable solution to the human condition of chronic disappointment is to stop clinging to the hope that we will find something in this life that is not disappointing. Through meditation, we come to see the ultimate truth of the universe and escape samsara for the deathless.
I would not dare to say that Trump could not possibly have a flash of awakening at the moment of his death, or sometime soon after, but it seems far more likely that he has accumulated enough bad karma in this lifetime that he will be back for many more rounds on the wheel of samsara. We should feel compassion for him. If anyone gets the chance, you might try to explain the problem to him, although one doubts he will listen. But compassion would dictate that one at least try, given the opportunity.
A more subtle implication of the Donald Trump Rule is that we all need to stop trying to make the world what we want it to be. Another way of explaining Trump’s predicament is that he seems to believe that he can force the world to conform to his wishes. So he proposed as a candidate building a wall at the southern border to stop undocumented immigrants from entering the country and changed the rules for persons seeking asylum, such that the federal government now prosecutes them and takes their children, housing the asylum seekers and their children in deplorable conditions.
He issued an executive order — his favorite device for making laws, because he can utter them unilaterally, without having to cooperate with anyone else — prohibiting the admission of aliens from several nations that have mostly Muslims populations and denounced the judges who struck it down as violating the Constitution.