Practicalities aside, money is also how our culture defines value, and being told that what you do is of no ($0.00) value to the society you live in is, frankly, demoralizing. Even sort of insulting. And of course when you live in a culture that treats your work as frivolous you can’t help but internalize some of that devaluation and think of yourself as something less than a bona fide grown-up.
For most professional photographers, this should not be news. But photographers new to the business should pay attention.