It's one of those things theists ask me: If I don't believe in a God or an Afterlife, if there is no higher purpose, why bother living at all? Might I not just as well die and save the hassle? What difference would it make if you'd die today rather than in 50 years?
For some reason, they think this to be a very profound question. It really isn't. In fact, I find the question rather preposterous. Whoever asks it is implying that if they wouldn't believe in a God/Afterlife/Higher Purpose, if they believed life was finite, if believed that life ends at the grave, they would certainly not bother living - Which I think is a rather pathetic statement to make and a testament to a lack of serious consideration of the matter.
Let's try an analogy: Why do you ever go on a holiday trip even though it inevitably ends? Even though there is no higher purpose to it other than that you enjoy it? How can you enjoy a sunset over a beautiful beach if the time you spend there is finite, if it's only two weeks before you'll have to go back to the same old life in the office again?
If theists were actually serious about this mindset, I should expect them to step out of the plane, take a look around the astonishingly beautiful place they've landed, frown, and say something like:
"Pff... yeah it's nice, but so what? How can I enjoy this stay, knowing I have to leave eventually?
Of course, if there was a book subjecting me to nonsensical rules during my stay and promising me that, if I subject to these rules, I get to go on an even better, eternal holiday after this one, then, and only then! could I enjoy my brief stay in this wonderful place."
So, does it make a difference whether I die tomorrow or in fifty years? Certainly not to the universe, that's true. Maybe not even to other people, though I like to think it does. But be that as it may, in any case it does make a rather huge difference to me, and I don't know why I should need any more incentive than that to go on living. I am not opposed to suicide; If you are in full control of your mental faculties and make the informed and well-considered decision that your life really just isn't worth it any more, I think it's your right to end it. But as for me, well, I really like living. For now at least. I enjoy my life, and I will go on living it as long as my life stays enjoyable. So the short answer to "why do you bother living?" is because it's fun. Being alive simply seems to be a more enjoyable state than 'not being alive' - so I'd rather live than not.
In the end it's simply a pretty nonsensical question to start with. Living is a bit like having sex: Affirmative is the default position. The question shouldn't be Why?, it should be, Why not?