Don't you believe that is a dishonest answer. How did you determine that you would exist? You had nothing to do with it, right?
Some very good questions.
Let me get the help of someone smater than me.
"I think, therefore I am"
René Descartes
See Descartes could not figure out if he existed.
"But I have convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it now follow that I too do not exist? No: if I convinced myself of something [or thought anything at all] then I certainly existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case I too undoubtedly exist, if he is deceiving me; and let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think that I am something. So, after considering everything very thoroughly, I must finally conclude that the proposition,
I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind."
He needed one truth where he could stand.
"Archimedes used to demand just one firm and immovable point in order to shift the entire earth; so I too can hope for great things if I manage to find just one thing, however slight, that is certain and unshakable."
And the only thing he could prove was that he was thinking; his one truth.
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I could not go through my entire life questioning why I existed; it had already been 5 years of being a complete zombie. I had to reach a conclusion if I was going to live life. Much like Descartes needed to define if he existed.
Why do I exist? I want to
You need to find one thing to stand on and build from there, but do not go through life so preoccupied with it's meaning that you forget to live it.