The modern world can't be an easy place to live in for those who are born genetically predisposed to crave absolute power over others. I mean, these days, any would-be totalitarian has only a very small chance of being born into one of the world's few remaining overt dictatorships, and a much greater chance of being born into a large Western nation that is nominally democratic. While fulfillment of the megalomaniac's innate drive is a walk in the park in a dictatorship, it requires all sorts of protracted subterfuge in a democracy. Bummer.
The main problem with giving free reign to one's dictatorial leanings in a democracy is the whole 'citizen's rights' and 'Rights of Man' thing. How is any self-aggrandizing despot to lord it over the masses, and watch them squirm and suffer and beg, when everyone seems convinced that there are not only democratic and legal rights but also natural 'inalienable' rights that come with just being a human being? Ideas that everyone is 'created equal' and has the right to life, liberty and the pursuit of happiness etc. can cause a lot of problems for the average authoritarian. Naturally then, in any democracy, all those rights would have to be removed before any oligarchy could transform citizens into subjects, and they'd have to be removed under the cloak of 'protecting' the very rights that were slated for extinction. A tall order indeed, but there are ways to do it. One tried and tested way is to create a foreign or external threat from which the people of a democracy must be protected. All sorts of draconian laws that subvert civil rights can be passed to combat this 'threat', and if the 'threat' can then be made internal or domestic, and suspicion of 'siding with enemy' cast over the citizens, you're well on your way to banishing those pesky legal and natural rights.