Hence why it's a causal time loop. Event A causes event B which in fact causes event A... ad infinitum. It's like the chicken and the egg scenario, except in this case the answer is both came first because everything has happened. And it works within a 'closed' timeline. We only get problems when we try to work it out from a point within the timeline/think we can change events.
Ah well now we're getting to one of the real philosophical questions to do with this theory of time. It's the classic problem of fate. Why do anything if everything is determined (and some people actually claim to believe this, though in my opinion they're just fools who haven't bothered to think things through)? This question pops up in other branches of philosophy. I did my dissertation on the topic of whether a belief in God is compatible with a belief in free will, though you don't even need to consider God - you get similar problems by considering the case of causal determinism in itself.Why would he do this if there is no point?