You could have been knocked out, and in a coma since you were born, this is all a dream, you live out your life in this dream world, when really you're lying on a hospital bed, wires coming out of you everywhere, and one day you'll wake up from the coma, and all this you see now, won't be there anymore, and you'll be in the real world.

You (when you read this, i'm talking about you, everyone who reads this, it could apply to you) could be a brain in a jar, in a place like "The real world" in the Matrix, and this is all a projection, you're just a brain, in a jar, seeing all this, dreaming it all, if you will, and none of this is real, the real world is where you really are, where your jar, that a brain (you) is, is the real world, all this you see around you is just what you are thinking and imagining as a brain