Because when you drink from a stream, you never know what is upstream. There are beavers and other animals that have all sorts of diseases, and their excrement washes down. There are parasites in water too.
I heard of Montezuma's revenge, I guess this is Crazy Horse's revenge (he ended up living in Canada) but really, I think it's that green part you mentioned.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.