Sincerely, do not read this if your mental stability is tenuous. Basically details the numerous factors, environmental and otherwise, that are all pointing to societal collapse by the 2040s. I could barely get through it without feeling nauseous. There's some minor liberalism regarding China but it's more of a footnote than major focus.
Making a self contained livable homeostatic enclosed system is crazy difficult, as far as i'm aware it still hasn't been achieved even in those large experimental biodomes, let alone some underground concrete bunker.
What‘s the problem? Water? Electricity?
Everything basically, if you don't have an external water or air supply then you need internal systems that basically mimic the real world but in like 0.00000000001% of the space. Say to make enough oxygen you need x amount of plants, you will need a certain amount of plants for food also, but to support those plants you/others or some animals need to make enough co2 to support them. Getting this correct on a small scale is incredibly hard and as things can fluctuate a lot more due to the smaller scale (say all your potato crop gets a disease and dies) you can have everything end up spiraling out of control and all being dead very quickly.