actuarial studies is pretty brutal in its dropout rates, so it may be a good idea to not go into actuarial studies if you are not able to get at least the minimum ATAR. I would expect transfers to not fare very well.
@quickoats could comment.
First year wasn't
too bad but tbh I think the mythical dropout rates come from the really hard final qualification exams, and people switching out because it's not what they thought it would be/are bored of insurance (i.e. me). According to the UNSW timetable there are roughly the same amount of students in year 2 and 3 actl so yeah not a 50% drop out rate. I will note that there are about half doing the optional year 4 subjects (known as part 2).
The real bottleneck is grads going for grad roles - you NEED to have an actuarial specific grad role if you are looking at becoming a fully qualified actuary (as most actuarial studies students probably do). There are a lot of UNSW, MQ, ANU, Melb, Monash, Curtin and Bond (lol) students competing for a very small amount of positions, so the WAM probs needs to be quite high + extra curriculars to have a shot. Inevitably, lots of people miss out, but might not have enough statistical/computing/accounting/financial knowledge to make the jump into other fields.
Please try to ask yourself "why actuarial studies?" - if you feel like you have a good enough reason for doing it, then go for it! But it's really not all that it's made out to be.