You should stick school out till the end, even if you do badly in your hsc these years are an experience that you wont ever have again and you'll be suprised by how much that may mean to you some day. it's not worth giving up just because you may make mistakes or not do as well as everyone else (unless your school is rife with bulling and is making you depressed, then you should see a school councilor about changing schools to somewhere that doesn't suck)
And as far as university goes, I will agree that uni isn't a requirement of sucess. My father dropped out of uni because he decided that the costs of the degree weren't worth the benifits of the jobs he could get from it, so he used the skills he learnt from personal experience and his schooling to start his own buisness. 30 years later it's still going strong, its not a million dollar industry by any stretch of the imagination but it has been more than enough for my family to live and live very, very well. The point however is that success is never a given, you will need to work very, very hard to get a job without a degree, especially since most of your competition will have degrees. If you want to make your own buisness then you will need to have some way to seperate yourself from the competition (many of which will have degrees coming out the wazoo) as well as the luck needed to get that sort of thing off the ground, so dropping out of uni will be the most difficult option of the two, are you willing to go through with that?
And thirdly, all the people you listed started their careers many decades ago. Back then a lot less people were able to get degrees or develope the skills of bill gates and steve jobs, so the need for a degree was less necissary for them. Today things are different, more and more people are capable of getting degrees and succeeding. If you can't stand out from that crowd then you will be left behind, thats just natural selection.
