Wow man - you are gonna get really tense looks from people. I don't think it was any of your business if I'm being honest. Despite that, cheating is wrong however you've got to personally aim to achieve better than other people. If you know you are capable of achieving similar grades, why report it? In my opinion I really think this was a waste of time, it could have put to better use such as actually studying. You'll be going against thousands of other students who are doing exactly the same thing, so what you are doing is completely irrelevant. At the end of the day, one person is not gonna make the difference to your grade - its up to you if you can make that difference.