True. My brother is the smartest person I know (and I've met people from Ruse, North Sydney etc), and he received an ATAR of 45 only because couldn't give 2 fucks about anything. In saying that, he was very passionate about woodwork, and he would work on his major every chance he got to perfect it. The end result was that he won an award, and he received band 6. Goes to show that its only really about the effort you put in, and not how smart you are.
At the end of the day, an ATAR is a rank. It shows you where you are amongst everyone else. It is not a measure of intelligence. After you recieve an offer for uni, ATAR won't matter. Also, you could still get a shitty ATAR and make your way to the course you want. My mate, received a 52, completed one year of B/Sci, and has now transferred to Law/Arts. He put minimal effort in HSC, and he still got to where he wanted. It doesn't really matter. Don't waste your time reading those "99.95 only, will be so disappointed if I got 99.90" threads because BOS has sadly been transformed into a tafe-hating, ATAR below 95 shaming, negative environment, and make people feel less smart than what they actually are.