Milgram set up a lab whereby subjects were told that they were to read a multiple choice questionnaire to another subject (who was really an acting accomplice with the research team) who was to give an answer. The "teacher" was to give the "learner" a series of increasing shocks should the "learner" give the incorrect answer.
Take a moment to watch the video below of a similar experiment carried out more recently, but with the same disturbing conclusion.
1) People are very likely to go ahead with whatever orders are given to them via authority figures. To most people, the fact that the authority is giving the order eliminates their responsibility over the situation. If they are able to defer responsibility to whomever was giving them direction, most people are apt to carry out a lot more terror than we would normally think possible. This makes sense because from the moment we are born we are taught to obey and respect authority, from our parents to our school teachers to the government and governmental bodies. Most people have it ingrained into them throughout their lives that they are to respect figures of authority.
2) If people believe that whatever they are doing is for a greater purpose, they are much more likely to carry out tasks that they would normally not engage in. In the Milgram experiment, the "teachers" were under the impression that what they were doing, in spite of the fact that their actions were delivering what they believed to be a significant amount of pain to the "learners," was for the good of science and was a necessary component (as continually assured by the scientists) of the experiment. In Nazi Germany, the soldiers believed that what they were doing was for the good of the country. And Germany prior to the war had been in a dire economic situation, so the people were even more so willing to believe that their orders were sound and necessary.
So in the case of Chavez, he preyed on an impoverished populace while sprinkling in popular anti-American rhetoric to charm the population to the point that he was able to do insane things like make it a law that every single channel on TV had to air his speeches while banning and shutting down any television stations that were critical of him. That's to say nothing of some of the other marvelously insane things this guy got away with.
The world is going to continue to see dictators rise to power and flame out, because their rise is almost inevitable given poor economic conditions.
But before you try to make the claim that you would never carry out egregious acts and you would never follow the rule of a dictator, remember that in the Milgram experiment, it wasn't a "significant" percentage of people who would carry out the shocks all the way to the point of death, but rather, it was the majority.