The core problem is how Capitalist presents itself in film. It is very key to take some time to think about how Capitalism is expressed in media that is dominated by and funded by Capitalism.
Please indulge me, I wrote a number of papers on this in graduate school.
Firstly in the world today only Capitalism makes films, and only profit motivates films. The government does not make films, it does not support films with grants or bailouts. Regulation of film is just political side show, with the GOP actually wanting more regulation of an industry, why? Because its not real regulation.
Now film making is very expensive, taking a film to product is on the level of cost like making a new weapons system. With no public investment at all this is a massive fully private industry, with very big money involved, a fully Capitalistic global industry.
Okay so Hollywood is perhaps the perfect global market.
So people who support Capitalism must love Hollywood right?
Well no, actually the opposite, this most Capitalist of industries, most global industry in the world finds it product, which is the perfect global commodity represents Capitalism in a way that most Capitalists find offensive. Odd that eh?
Well its not so odd when you start to think about how Hollywood is making a Commodity that includes its own justification. Justification or ideology is the lies told by power to make their order viable.
For global Capitalism the process of making money off a every growing global community that need to be converted to Consumers so that they will be driven to work in factories, put up with environmental and economic exploitation, and ever growing debt.
Now normally how this is done simply by worshipping wealth itself. But the rich are shown in Hollywood in a very crude animal manor, they enjoy drugs, sex, violence and creativity.
But beyond wealth when the subject of Capitalism comes up things get a bit more difficult.
Hollywood is a market, so it can't just produce educational videos about how great Capitalism is that bore people. They can't out right lie, so they generally tell stories that admit the negatives that people see, but introduce concepts that the evils of Capitalism are not the evils of Capitalism but the evil of bad people.
We see time and time again films about Capitalism show Capitalists acting badly, but not doing it by necessity of market forces but because they are evil. Real Capitalism seems rather banal and boring, with people making budgets. People don't make budgets in films.
So the Fountainhead worked perfectly as a film, because it played the myth of Capitalism perfectly.
Atlas Shrugged simply makes no sense in terms of cinema. The villains' and hereos' motivations don't work as a movie. Unlike books films are short, they require that the audience already know the plot before they ever show up. That is why good films and bad films still follow the same structures, they have to. You can't construct an entire universe out of raw cloth and get wide range approval. Films that do this are restricted to art houses or YouTube with a small audience.
But Rand's work has to be the biggest success, because it can't exist on its own. Rand's work can not be read as just books, because it obsession with Capitalism is so strong the reader is going to think 'how much money did this make?'
As a book it is more open for people to be taken down strange roads like Dune, and its possible for stange books to sell enough over time to be Bestsellers. For Dune it does not matter if its a best seller or not really. Most books it does not matter how many they sold.
But for someone as fixated on Capitalism as Rand it is utterly essential for it to be a massive best seller.
But any movie made about Atlas Shrugged and still being able to be called Atlas Shrugged is going to need to show Capitalism in a way that is not fit the easy excuses for the nature of Capitalism the audience needs to understand globally.
Summing up, Atlas Shrugged because of its content cannot be a major Hollywood blockbuster, and because of its ideology it has to be an major Hollywood blockbuster.