1) Seems rather abstract or general.
2) The first sentence starts "Assume there is a resource pool" Why
should we assume that? You have not explained relevance, set the stage, or motivated the reader - you are merely launching into a lecture ... fine if you are a college prof who has a classroom of students for Econ 101, but otherwise, people probably won't care. You need to frame the essay to be relevant - it must pass the 'who cares?' test or the 'this essay is important because ____' test.
3) Who is the audience?
4) Two consecutive paragraphs start with the word "Now"
5) What is your thesis sentence? Does every other sentence you wrote support that?
6) Your last paragraph should be a summary/close the deal affair, but you opened new issues there ... how do we know that internalizing the costs is sometimes not worth it, and that people should be allowed to push the costs onto others? There are huge ethical and economic questions related to that, yet you raised such thorny questions and simply say it is so ...
7) The 3rd paragraph is poorly crafted.