Ever thought about that some people actually need to 'study really hard' to even get 70 ENTER in the first place? Or that some people's definition of 'studying really hard' isn't the same as another's? And really, I don't know what you're basing this off. Even being in MHS, I saw plenty of cbf and demotivation prevalent throughout the year with most people just wanting an ENTER enough to scrape into their course, or just not caring about it literally at all and just hoping they'll get into something. At public schools and so on, I further doubt that 'even the sloppiest guy' would be so motivated. There are a select few, but it's not everyone. However for those who do bother, it's a bit like some model I learnt at uni; there's people who are achieving learners who just learn for the sake of competition (quite a large driving factor for me actually), and then there's those who learn because they actually like learning (think of the Maths geniuses on this forum). I think the predominate reason that causes people to start trying is the achieving one where because VCE actually assigns quantitative scores to everything (SAC scores, SS, ENTER etc.), people actually have a drive and a means of comparison at where they stand, and this brings out their competitive spirit I guess. And not to mention of course, that their futures are (apparently?) on the line with regards to their careers and so on. This is a reason which might predominate for those who have a bit more foresight and initiative.