I think they meant more like "people band together to pay Christophe Nolan to create some new film" ala crowdfunding. Is that a sustainable model for the world economy? Unclear.
There would likely still be some demand for the experience, but the tickets would need to be more expensive to recoup the costs of making the film. At that point: it does seem like people pooling together their funds to fund the movie itself isn't insane. The point is that the "investors" wouldn't be investing in the hopes of a financial return, they'd be paying for the creation of the film.