Existence is play. Communication is play. You throw a ball of words “out here”. I caught the ball (read your words) and I’m throwing it back to you (responding). To me, you exist, because the ball came from someplace and arrived into my eyes. I threw the ball at somewhere. I can’t guarantee that I will be understood (that anybody will catch the ball) but I knew someone threw it at me, and I threw it back. Therefore, to me, you exist as the thrower of the ball.