The real reason Rapture fell is not unregulated capitalism, but inflexibility. Yes, Andrew Ryan's philosophy was detrimental in a lot of ways, but players and fans of Bioshock are too quick to simply blame things on just laissez-faire policies alone. To be quite fair and clear, Ryan's Rapture wasn't even entirely laissez-faire, either(and I know that sounds exactly like the "that wasn't true socialism" argument.) But, in this fictional world, it's more true here; Ryan's few rules and the way he enforced them were the biggest contributing factor to Rapture's fall. That, and his complete inflexibility to change driven by his own fear.

Andrew Ryan's fear and paranoia killed Rapture. Not his policies, not the Great Chain, but the creeping, shadow-jumping fear of the Bolsheviks, government agents and the bomb.

The true test of a civilization is the test of time, and it's almost always easier in the beginning. Maybe not in the very beginning when a civilization has yet to be established, by far harder than breaking ground is making it last. The test of seasons. Ryan had groups of like-minded individuals to build and support Rapture in the beginning, but as time dragged on, fewer people shared his vision. Division developed between Ryan and the people.

At multiple times, it's illustrated in the games and the book Bioshock: Rapture by John Shirley, that Andrew Ryan personally had decisions where he could've averted things, eased the tension and pressures people were facing. He chose to ignore his people, his critics and everyone else and keep to what he firmly, unshakingly believed in. But, he didn't even fully practice what he believed in, as he enforced his rules on others, unflinchingly.

The Bible was banned in Rapture, so Bibles were smuggled in and a church developed in secret. Travel to the surface was banned, as were certain goods, so a black market developed. If Andrew Ryan had simply eased up on his laws for Rapture in these areas, it would've made it harder for Frank Fontaine to establish himself. Instead, the climate of fear and pressure, among other things, made it the perfect place for Fontaine to create a criminal empire.

Ironically, Ryan's fear of "the parasite" allowed a big one to develop right within his own city.

There's talk of a new Bioshock game. Honestly, I have this idea to explore a fallen Communist/Socialist city-topia on the moon. All the red from Soviet or Red China's artworks would look well with the pale white of the moon. And instead of plasmids, maybe something with dark matter, or some other sci-fi stuff. Big Daddy-type baddies in spacesuits. Not the most original idea, but still something I'd love to see.

Ultimately, ideologies are just ideas, and like the people that make them, none of them are perfect. But, it is people who make those ideas into reality, and sometimes what makes them fail is being blinded by the ideal to the point where the person believing in it can't see the reality around them. Until everything is falling apart.