Here's a really good reason why you should think for yourself: if you don't, civilization as we know it will crumble and the streets will run red with the blood of the innocent. So that second part was fabricated, yes. The first part, about civilization crumbling, appears to be for real.
I say this based on an interesting news brief in Nature about two researchers, a biologist in Nova Scotia and a cultural and environmental scientist in California, who have come up with a new model for why societies suddenly fail. In short, they stop innovating.
There are two ways we humans learn things, through individual learning and through social learning. The former is the first guy who ever poked at a cactus to find water; the latter is all of the people who learned that you can get water from a cactus because the first guy told them and all of the people they told and so on. Human societies benefit from a mixture of these two types of learning.
Individual learning leads to new advancements and ways of thinking, but it's costly in time and effort: Imagine how little we as a species would have progressed if every time one of us was tasked with cooking we had to discover fire after much thought and humiliation. Social learning is far less costly, but it leads to stagnation, especially in periods of calm. During calm times, we have less need to use individual learning. Unfortunately, we also tend to deplete resources quickly, since societal thinking is generally based on a discovery that was made in a previous context -- say, when there were plenty of trees to fuel that fire. Resource depletion, by the way, commonly leads to societal collapse. We tend to use more individual thinking in times of upheaval. Since we're faced with new challenges, the traditional ways and means passed down through social learning don't apply any longer, what with the sky falling and all.
I can think of a modern example. Oil! We're about to run out, but we still rely on the same socially-learned methods of powering the world. Hopefully the few individual thinkers working to thwart collapse can come thorough and save the rest of us idiots or else that whole blood in the streets thing probably will happen.