Why do so many people doubt that there are still creatures we dont know about ?

Looking over some answers on here about things such as the lochness monster bigfoot mermaids dragons werewolfs and many other things of the same category it seems like everyone says right away there is no way its impossible we have no scientific proof . Scientist in my opinion don't open there minds enough some species believed to be extinct have been proven to still exist i don't think anyone should make the comment a species has died out the only real way to know that would be to see every place on earth at once there is still alot of the world we have not explored. Now with things like werewolves i don't think it would possible for a human to shift back and forth between a human and wolf but i think there must be some truth to it maybe a new species of wolf or something related but there is no way to say either way is impossible . there will be people who leave paragraph long comments proving why it would be impossible but they leave out the history and accounts and origins of it just showing reasons why it probably does not exist is in no way proof it does not. And when ever there is sighting photos or videos people always say its faked or photoshoped well anything can be photoshoped but that does not mean it is and with everyone saying im not beliving it till we have some evidence there are so many people saying they have seen these things or that they maybe even are one of these but when we right away say they are lying there is really no way to know. i might have said a few thing wrong i typed this pretty fast i just wanted to say my opinion and know what people had to say about it thanks :)