Why we are born if we all going to die?
Answers
Life: Your actions during your life affect the future of people who come after you, sometimes a little, sometimes a lot and sometimes for better and sometimes for worse. That is the point: each person's life contributes to the world, to its evolution, to its culture, knowledge, gene pool, energy usage, progress and regression.
Death: Your death makes space for more people, ideas, methods, improvements, disasters, problems and solutions; it also helps the world move forward; and everyone who lived and died before you contributed to what you are and will become.
What's in it for you? A life. Possibly a very good life, possibly not, but it's an amazing thing to have anyway.
The purpose of living is discovery. Once on this path, your desire to know will drive you towards choosing uncomfortable reason over safe rhetoric. Then, reason will reveal itself as more fantastic and optimistic than you believed possible.