"Monopoly by the People"

Today we saw in class a now topic: Economic Systems. It attracted my attention immediately after I heard this systems decided who controlled resources and prices, which has a huge effect on almost every matter in our world, since resources and prices practically rule human behavior and action.
  After thinking a bit I decided that, according to my opinion, a Planned Economy, ruled 100% by the government, who decide how to manage resources and prices. This would be great, since it would be like a single, pure, total monopoly; this might sound evil, but if we think through, we will realize that it would be the monopoly of the government, meaning us, since the government is our representative, ending in no owner of the world.
If we look around we will notice that a lot of our economic and social problems are caused by competence, specially by big companies, which constantly struggle to get more profit, taking some actions that affect us greatly, but the worst part is that all this profit goes to very few people, the owners/investors of the company. In a planned economy all that profit would go to the only company in existence: the government's; which in time would get to us. And that's not it; the government would control prices, meaning they could be adjusted to the people's needs and desires.
However, in the other hand, this system would be very dangerous, since corruption could completely rotten the system, putting all the power in very few people. We would need a lot more social and moral evolution to ensure a pure functioning of this system. Also. since there will be no competence between companies, many technologies would get stuck, all because the companies doesn't have to worry for loosing it's costumers, being the only one in existence.