Amy
Here it is. Even in your world, only not many know it so those who talk about it can be seen as insane or brushed aside because there is no proof. Because the greater knowledge says that they do not exist, that is what is accepted. In my world, they do not and it took adjusting to accept it and even now, I still prefer to rely on what I know, logic. Had I not appeared in the future in a new country with the proof, I never would have believed it.
Honestly, it is quite similar here. Those of us who show up, we know but the general population remains unaware. Sometimes it is easier for people to ignore the things they cannot explain, to find a more 'common' explanation.