Kameron Hurley wrote an excellent essay on "The Sad Economics of Writing Short Fiction." All fiction writers and aspiring writers should read the essay. I generally agree with most everything she said.
It's absolutely not economically sound to write short stories. But ... important point ... it's also rarely economically sound to be a novel writer or any type of fiction writer.
Yes, there are authors who make a full-time living from their fiction writing, but their numbers are rather small. In the SF/F genre maybe two dozen authors make a living solely by writing fiction. The rest of the genre's authors, including many award-winning and bestselling authors, have dayjobs, a significant other who supports them, or do editorial or other freelance work to make ends meet.
For more on what most authors earn, check out this survey from last year. Be warned: It's depressing.
My point isn't to say that authors shouldn't be paid a fair wage, or that people can't succeed financially as authors. They should and can. But if you become a fiction writer merely to land a financial windfall or economic stability, you are a fool. There are plenty of far more reliable ways to earn far more money than by writing fiction of any length.
If you love short stories then write the damn things. If you love novels by all means write them. And when you publish these stories, make sure you're paid a fair amount for your work.
But if you love money, understand that fiction writing will likely never let you pull wads of cash out of your butt in a never-ending shower of green.
Ugh. That last mental image probably didn't need to be there. But I'm a fiction writer. It's what I've always wanted to be, so I can't help creating vivid if at-times disgusting fictional images. Even when I'm not paid a decent wage for doing so.