Betrayal and revenge
Why is President Duterte so sensitive to criticisms about his aggressive campaign against illegal drugs and corruption in government? Because these constitute the only promises he made prior to his election. If he made passing references to something else, these were made mostly in answer to questions or in accordance with some pre-set topic of discussion. But the bread and butter of his candidacy was illegal drugs and corruption.
Now Duterte did not run a conventional campaign where a candidate would woo the people for their votes, where a candidate would employ every trick in the book or sell the last carabao of his cousin to try and ensure his victory at the polls. Duterte was the only candidate in political history to outline a plan and then tell people not to vote for him if they disagreed with that plan.
It was that simple. It was an uncomplicated campaign. When Duterte emerged the runaway winner, it is difficult for him not to see that as an overwhelming sovereign backing by the Filipino people for his plans. If the leader of a country has that kind of sovereign backing from his people, it becomes easy to see why he would react violently when the leader of another country, like US president Barack Obama, tries to tell him what to do in his own country.
Filipinos and foreigners alike can say what they will about how Duterte reacted to Obama's intervention. They can call him unpresidential, undiplomatic, even crude or uncouth. But even if they throw the book at Duterte and follow it up with the kitchen sink, they still miss the whole point of his tirade. For the issue is not about how Duterte reacted. The heart of the matter is why he reacted in the manner that he did.
In other words, it is immaterial whether Duterte