Yes, of course. They're not the only picky ones, though.
For instance it's very common for income debates on HN to be full of comments about how people "cannot live on 12k/year."
Replace 12 with whatever threshold you think it is.
But they can, of course. I did for half of my adult life. It's a matter of pickiness. I had roommates I didn't enjoy, I ate rice and beans and ramen, I cooked for myself, I drove beater cars, I had no cell phone or no phone at all. But I always had money in the bank and I could pay my bills. It's a matter of choices.
So yes, it's a matter of pickiness about the city. They're destitute in the country, perhaps, but they're living in the home their grandfather built, on the land he farmed, their cousin lives a mile up the dirt road, etc. Many of them aren't unhappy, frankly--people here have decided they are.
But they aren't sure they'll make a lot more money by moving to the city, and they're definitely unsure about how they'll like it. My best guess is that most of them wouldn't. I moved away from the city on purpose, so perhaps my perspective is skewed.
I would move back before I starved, but not much before that.