The future we saw before changes. Ben does not exist in the future. Ben is dead. The future that we've already seen Sayid shoots young Ben in the 1970s. Ben does exist in the future, as his 2004-ish self, now on the other island. Ben waits until time catches up, and changes the future. Ben waits until time catches up, and makes sure everything happens the same. Ben is not dead, just wounded. wounded. Ben's wounding affects his personality negatively, and leads to the purge. Ben's wounding affects his personality positively, and he does not commit the purge. The future stays the same. Ben knew Sayid had to shoot him in the past in order for the purge to happen. The future changes. Ben sent Sayid back in time to shoot his young self in order to ure we saw The returning 815ers prevent the purge from happening and thereby save the world. The returning 815ers make sure the purge happen anyway and thereby save the world. There is no purge, and maybe no 815 plane crash either. ready seen en waits until time atches up, and hanges the future. waits until time hes up, and makes e everything happens Purge, 815 crash still happen.. e same. Ben knew Sayid the past in order for the Purge happens. es. Ben sent Sayid back s young self in order to Purge doesn't happen.