I think there are mainly two reasons for this:

1. In fiction, you’re simply not personally affected, so you don’t have to face any adversity or negative consequences. It costs nothing to see yourself as part of the revolutionary movement, and you don’t put yourself in danger.

2. Apparently, many people simply don’t want to admit what monsters their leaders really are, even though it’s actually obvious. This is the result of decades of propaganda, I think: The U.S., for example, has always seen itself as the friendly superpower that brings freedom and democracy to the world. Now that it is obvious even to the biggest idiot that this has always been a lie - since the regime has abandoned the facade - people are looking for other explanations to maintain the worldview they have long held to be true - such as the excuse that the current U.S. president is being controlled by evil forces from other countries (Russia/Israel) and therefore does not represent his own, indeed so righteous, country at all.