Many of them are religious and believe plenty of things they didn’t directly observe. It’s more that they have been trained through religious thinking that if someone confidently claims something it must be more true than someone who honestly admits that “it is the best we can know right now and we will update our understanding as we obtain more evidence.” These people need the answer now and that answer can’t change because changing your opinion based on new evidence is seen as weakness and opinions should be handed down from on high and never change.