yeah, I was thinking about that.  if you follow a straight line, it might indeed be the case that you're more likely to get to the restaurant at the end of the universe ;-) than to a star, but then there are space-time distortions that might change the picture.  now, if the "up" direction is a cone rather than a uni-dimensional straight line, then perhaps the odds of encompassing a star or even a whole galaxy cluster may get closer to 1 than to 0.  I wonder what angle would be enough to make it a near certainty

you're most certainly right about the challenges of getting to outer space in a balloon.  as the atmosphere gets thinner, it becomes harder and harder for the equipment to be less dense than atmosphere, let alone for the density difference multiplied by the volume to balance out their slightly reduced weight