It always amazes me the types of things humans come up with to eat. I can only assume the origins were from necessity and became part of culture, rather than someone's idea out of the blue or for a dare.
Key trick to eating natto is adding a dash of soy sauce in it, makes the dish so much tastier and honestly it’s pretty yum, if you don’t eat natto alone and add other seasonings etc.
As a french person I find it funny that you think blue cheese smells bad. I mean we have Munster, Maroille and a whole bunch of other cheeses that smell a hundred time worse and that we love dearly. :)