Why do soldiers who work for a tyrannical dictator decide not to stop him?

I never figured this one out. It seems that whenever a dictator who is obsessed with power and control have enough soldiers to back him up, the soldiers do nothing to stop him. Did you ever wonder why these soldiers do this? It makes no sense. The corrupt dictator doesn't want to share power, but wants to be on top. The soldiers don't care about that? The soldiers don't care that they are working for someone that doesn't even care about them? Do they only love power when it only comes to making money, or being loyal? I just don't get it. A perfect example of what I'm talking about would be Hitler and his soldiers. I never understood why all his soldiers who stood at his open speeches just didn't decide to open fire on the guy while he was speaking in wild tongues. Am I the only one that thinks these soldiers who work for corrupt war mongers are too ironically cowardly to be soldiers in the first place? What do you think?