some photographers have a few camera bags, not just one. imagine a scenario where you have:
4 lenses (imagine 2 regular-sized and 2 huge lenses)
a hoard of accessories
you buy one huge bag to store all of them.
but one day you decide to head out to shoot the streets and decide on just 1 body and 2 lenses.
are you gonna use the HUGE bag, or will you have a second bag for such situations?
so, get a bag for use now, and think about a bigger bag when you get there.
and honestly, if your parents are paying, tell them that gear protection is necessary to spend that amount.
but my advice? pay for it yourself. it's more satisfying that way.