I don't doubt there is possibility of getting everything in any situation
but chances are slim
sometimes we should not even aim to gain everything
when we do so
we increase the possibility of ending up with nothing
exponentially, at least to me

Then again
why settle for one when there are chances of having both (or all or whatever applicable)
where does the answer lie
well, let's see
does gaining everything make things perfect
if it does, stay away from that goal
what we should aim for is to better our lives
maybe by gaining one or two
coz perfect is non-existent

Its not about being pessimistic or whatsoever
more of realistic than anything else
if one finds it hard to think that way
the first step is to be thankful for what you have and treasure that one or two things you gained - of coz, which betters your life

A safe distance