Leaving a restaurant - leaving a country

Today, I decided to grab some Lebanese food from a newly opened restaurant close to my house. Inadvertently, a discussion with the Lebanese store manager about the old TV show "Fame" somehow turned to discussing the movie Syriana and the assassination of the prince at the end of it. By some mysterious influence (Lahoud?) the manager started drawing comparisons between the assassination of that prince and the assassination of Hariri. He was clearly hinting that the Americans had either killed him or greenlighted it. After a few split seconds of me debating with myself whether to shut up or shut him up, I decided on the latter. Pretty soon, he started spewing off one conspiracy theory after the other, providing "alternative" versions of ancient history, modern history, and present day politics (One example of his ramblings is that the US and the UK supported Khomeini against the Shah whom they wanted to get rid of...). I struggled hard to understand what he was saying, to find the logic in his claims. Naturally I found none.
How do you debate or discuss with someone who will have a conspiracy theory to explain every event, every calamity that befalls us? I tried in vain to explain that we need to stop blaming others for our misery, to stop allocating responsibility to everyone but ourselves. I argued and argued and argued. I argued that we have to fault ourselves for failing to build the democratic state that we (I?) desire. I argued that no one internal group should have the right to dictate war. I argued that it was the responsibility of the elected representatives of the people to do so, only through state institutions and legal means. I argued that given the lack or weakness of such institutions and of such a truly democratic process, it is our duty to strengthen them and create them... I got nothing! More deluded versions of past and present, some abstract references to throwing ourselves in the arms of the west, more abstract references to dignity.
Finally, I asked him if the entire war was worth it. I asked him if the "price" we paid for an action most of us did not endorse was worth the "value" that we all received for it... I got the answer I should have expected. We maintained our dignity so it was worth it.
At that point I realized there was no point discussing this anymore. There is no way that I could convince him of my point of view because he simply did not want to listen. That is fine, he wasn't going to convince me either. On the other hand, he had no problem endorsing the imposition of a point of view and its consequences on me(via endorsing the actions of an organization operating outside the realm of the state).
I thanked him for the discussion and left his restaurant, just as I had left my country years before - disappointed.

PS: The man was in his forties or fifties and had lived in the US and Canada since he was in his twenties...