Short stories are fun to write
I enjoy fiction, because I can let myself go. I can write about the couple I saw in the coffee shop who were having an intense argument. I can imagine how it felt to live in the Australian bush a century ago.
Here’s the thing about short stories. They’re handy to test ideas. Spending a year writing a novel, and then discovering that no one wants your tale of zombies which terrorize a colony on Mars, is shattering. You can write a short story about your Martian zombies in a a couple of days. Does it make sales? Yippee — write another one. And another.