They already try Galt's Gulches, over and over again in basically lawless parts of the Earth, and they fail pretty fucking fast over and over again, often from internal backstabbing and fraud.
Sure it fails when there's free breathable air, a comfortable temperature, many ways to simply leave, and it's easy and cheap to ship supplies, but what if none of those things were true, and also any equipment malfunction wasn't merely inconvenient but actively life-threatening?
They will actually, but not the utopia, but what really happened - some people will get all the wealth and they will be left with nothing in the desert.