Sure if I step outside my body and imagine looking down at the Earth and seeing thousands of people I could fairly say that any of them could ask the same question - why am I here and that would be no different from myself asking the question, but if you sit and think about it, what really is the "I"?
I realize that my consciousness exists because my brain physically exists and that becomes the "I", but it still doesn't answer the question of "I" being here and experiencing things instead of another "I". I also realize that if my brain ceases to exist that the "I" should cease to exist also, but why won't "I" be here again after that? Why won't it happen again? It has happened once so far from what I can tell now.
Another question I've often asked myself is that if my father had married a different mother or my mother a different father would I still be here or would it be someone else and I not exist?
Maybe I would be two "I"'s. The "I" that my father produced with another mother and the "I" that my mother produced with another father! or maybe I would be no "I" at all. Either way, it's amazing that "I" am here!
..... or maybe it isn't .......
