Tigger is half there - Molly you need to research Maslow's Hierarchy of Needs first......when I say Tigger is half way there, I mean that dictatorships or monarchies naturally thrive in 'poorer' societies - most of them that exist out there are relatively benign; however, on the 10% edge they become more threatening or 'despotic' as termed.
Lee Kwan Yiew of Singapore, a benign dictator, brilliantly summarised it for me over twenty years ago, "It is only when Gross Domestic Product (GDP) per person hits $20k, does the notion of democracy become sustainable........take the Far East, until recently there have been only two fledgling democracies in the Philippines and India - not even Japan until the very very recent times...or Korea or Taiwan.
When applied to the Middle East, only the UAE, Qatar, Bahrain and Kuwait qualify. Saudi is close at $17k but countries like Tunisia, Egypt, Yemen are way short of the mark, as is the Cote d'Ivoire. Libya and Iran come in at about 12k..........
Democracy has to be carefully chosen - and we must not forget that some societies like S-Arabia actually have some 'democratic' systems built into them such as leaders councils on every Friday that allow voicing of issues/problems from the local community through the leadership hierarchy, including the royal family there.....not our notions of democracy but something that is overlooked by western commentators......and one reason Saudi will remain stable.