>>719019335 (OP)
>How precarious is the economy in Fallout: New Vegas?
Very, that is the whole point. The strongest economical player in the region is NCR, and they are in deep shit. The war with BoS was a massive drain on manpower and costly, not to mention BoS nuked their golden reserves, which was a linchpin of their economy, as they controlled much of the civilized world's golden mines.
Coupled with is the apparent massive inefficiency and rampant corruption caused by the unchecked power of a small group of powerful brahmin farmers who continue to lobby for legislative that harms the majority of the population but increases their prospects.
Plus, their population just keeps balooning out of control. With them being pretty much the only functional state in the area, people flock to their borders in massive numbers, causing an immigration crisis.
This is why NCR expands towards Mojave in the first place, they desperately need more territory, and resources, such as power and water, which they can't supply in sufficient numbers themselves.
As for the other factions: New Vegas only exists BECAUSE of NCR. Their sole economic model is to leech off the (now tenuous) surplus of wealth NCR still holds. Their only real export article is essentially, luxurious services and unique space where NCR citizens can unwind in ways that NCR itself frowns upon.
That is why New Vegas remained dormant for so long.There was no point in brining it online until NCR scouts found it and thus confirmed that there is now a society that can be exploited. Without NCR, New Vegas has no way to make money, unless they somehow manage to strike a deal with Legion, which is unlikely given the disparity of their moral codes.
Finally, Legion is an inherently unstable organization. They can only survive for as long as they can conquer and plunder. They have no long term economic plan, not for now at least. It's a golden horde, basically. They talk of efficient trade, but that is largely a cope.