I think if anyone ever found out, their head would quite literally explode...
Although I also think NOBODY will EVER find out...
But I suppose you never know.
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So for now, we just give ourselves that reason.
It doesn't have to be a reason that supports the existence of all and everything in the universe, just enough to get you along content/ happy/ satisfied in life. Which is probably what we'd all want anyway.
Be it...
Your job
Your family
Your friends
Your partner
Your passion
Your beliefs
Your faith in the next life
Something else predictable
Something else completely far-fetched
Whatever purpose you choose your existence to serve
However many
Live for it. Remain loyal to it. Believe and maintain integrity towards it, despite the many deterrents you'll face. If you truly believe it's what your existence is for, you'll find a way for it to see you through.
Ugh... Just sounds like a sugar-coated way of expressing existentialism... But meh
