That kind of speculation is rather fruitless because there's no evidence that supports the hypothesis that we don't really exist. Actually, the universe behaves relatively predictable and so you still have to play along with the rules. You're probably not gonna say "this is all a dream so I might as well kill myself". Either way, you have a life and you're living it.
All that hypothesis can give you aside from cheapening our general understanding of the universe is perhaps a feeling of solipsism and existential dread.
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