>Photography, 1 decent camera is really enough.
Bahahahahaahhahahah... no.
1 decent camera is enough if you are not a photographer, just a person who likes taking pictures.
As a very amateur photographer, I do in fact only own one camera. The rest of the two bags is accessories for that one camera and several lenses, each of which serve a unique and useful purpose. Good camera equipment is dammed expensive. If I could buy less of it and still do everything I want to do, you better believe I would! I don't even do very complicated photography. I shoot exclusively outdoors in relatively bright surroundings. There is a whole other realm of lighting equipment that I haven't even entered into yet.
And just for some perspective, it is not at all unusual for professional photographers to carry two cameras at the same time. (With different lenses, since it takes several seconds to swap a lens.)
And that doesn't get into specialty equipment like medium/full format.
My two small bags of equipment is nothing compared to the amount of gear that an experience professional photographer is likely to acquire over the course of a decade or two.