alt Hacker NewsIt is a very weak ideological motivation for people who would never enlist in the first place.
However, I think people are generally too cynical towards a very real belief system. There are multiple examples of US pushing for democracy against its own interest. Bush with the Hamas Gaza elections, Obama with the Egypt Muslim Brotherhood government and Carter with pre-revolution Iran are such examples
Bush knew what he was doing - Hamas has the influence it has because the US wants it to have it. When Trump decided he wants them to release Israeli hostages he forced them to do it rather quickly, all things considered, showing who really controls Hamas. Restraining American "allies" is key to how America understands its interests and Hamas is an excellent lever to pressure Israel, or Hamas-controlled Gaza wouldn't be flooded with American and European money.
Similarly, Obama supported the Muslim Brotherhood because he did; in Ukraine for instance the same admin supported a coup against the elected government (this is not to say that Russia's actions in Ukraine are "justified", it's just a fact.) Democracy has nothing to do with any of this