It's a difficult question to answer, as "hardness" is subjective.
I believe that if you have some semblance of natural intelligence and you work as hard as you can, you will receive a 40+. I think it helps if you go to a good school (selective or elite private) with a strong cohort and motivated students, but there are many examples of people getting extremely high study scores in their local high school.
You can be "smart", but piss around in school and waste away your talent and receive a shit ATAR. Or, you could be "stupid", but work extremely hard and get a better ATAR than that "smart" person.
That begs the question - does it matter if you are naturally "smart"? In my opinion it might help a little bit, but the beauty of VCE (never heard that phrase before ey?) is that it doesn't test natural ability, it's a measure of how hard you're willing to work.
90% of the struggle of VCE is motivation, after that it's easy.