The actual answer is because the universe had to pick a finite number and it probably doesnt use meters as an internal measurement ruler for scaling so
Do you really believe that in all of eternity, we happen to be just four and a half billion years in? We are probably on our infinite life, and have infinite more to go. Just completely random lives, no idea where we will end up, nothing persists.
What’s so special with four and a half billion years (or 13.8 billion years, if you measure from the big bang instead of the formation of the Solar system and Earth) that makes it so weird for us to “just happen to be” during that time?