Besides looking at the set of stable democracies, there are other representative sets of countries that illustrate the same point.
Take the Arab-speaking world, for instance. Which countries would you feel reasonably comfortable spending a few years working in? Which could you conceivably imagine yourself buying a holiday house in, if you came into a mess of money? I am going to take a wild guess and answer the question for you. The Arab-speaking countries that fit this description, IMHO, are:
The United Arab Emirates
Until a few years ago, I would have put Tunisia on the list, too. And it would have been the only one that was not some sort of monarchy.
Which brings me obliquely to one more of the many evils resulting from the American Revolution. When the occupying forces set up a new government in Afghanistan, the logical thing would have been to invite the king back to form a government. After all, the only period Afghanistan has been a reasonably recognisable member of the modern 'family of nations'was under Mohammed Zahir Shah.
The failure to restore the monarchy - an institution that had moral legitimacy, and still lived in the memories of the older generation - was an act of gross negligence that led directly to the current mess.