I imagine that as a Levy I should be automatically entitled to all of
the honor and privilege of being a Cohen because 'I want the same
opportunity for spiritual growth and fulfillment that a Cohen has'.
Equally so, my older brother is first born. So 'I want the same
opportunity for spiritual growth and fulfillment that a first born
has'.
And this goes for many many things.
G-d puts each of us where, when, how, what we are. As I told my
daughter (when she said 'x' is allowed ....): if HaKodesh Baruch Hu
wanted you to be her sister (or her parents daughter instead of her)
he would have made you such.
Is it 'fair' that a Sphardi is allowed to eat rice on Pesach?? Is it
'fair' that in order to marry a bas-Cohen a man has to learn a certain
amount of Torah (and in some places prove it)?
The means to 'spiritual growth and fulfillment' for each of us are
different, since each of our souls has traveled different (previous)
paths and must correct different deficiencies within itself and the
world. Don't look at what the other person can (or should) do: see
what and how you yourself can grow and contribute.