Even when people change to the point it's undeniable, folks still won't let go of the world that's constructed in their mind through memories and conclusions that are like concrete. Caitlyn Jenner for instance decides to take on that name and embrace being a woman but many are going to have a difficult time not saying "Bruce" or "him, I mean her, you know what I mean". The world changes but we fight because it pushes against the structure of our mind which is rigid not malleable. But why are we rigid? Fear. Fear that when things change we will be left in the dust, irrelevant and wrong.
Things go extinct because they don't adapt. As humans we've been able to control our environments for so long that we haven't had to face that reality. The world both is and isn't what people construct mentally. It is in the sense that we can slow change down by imposing our thoughts and opinions on it but it also isn't what we think. The universe is something we know very little about and as someone said "there is a lot we don't know that we don't know". We either need to start opening our minds or become extinct in the process squashed by those who have had enough and won't stand for things like fundamentalism or ISIS.