Seriously, I can't understand that. Why do we support all those jihadist countries such as Saudi Arabia and attack secular states? Why didn't we support Qaddafi, Saddam and Assad who seem to be much better leaders than those of Qatar and Saudi Arabia. We are literally making the deal with the Devil. And that's why all those terrorist movements appear, because Saudi Arabia fuels jihadists everywhere around the world.
As another posted pointed out, our support for conservative monarchies is basically a result of the Cold War. We continue to do it out of the (probably justified) fear that the opposition would actually be even more conservative.
As to why we didn't buddy up with the secular dictatorships after the Berlin Wall fell, well, we probably would have if there human rights abuses weren't so bad. Iraq might have become an ally if they didn't invade Kuwait for no reason. Syria and Libya were on their way to become allies before they started killing their own people.
