Do you think it is possible for any billionaire to prevent collapse? Isn't this subreddit's premise rather that collapse is inevitable. If it is inevitable, then we can move past that hurdle and think about how you might use fabulous wealth to protect yourself and your loved ones.

A bunker in some location like New Zealand or whatever is just billionaire's version of prepping for collapse. A small timer prepper buys guns, soup cans, batteries, lighters, gizmos, and stockpiles oil and gas -- well, a big bunker is the same deal, just in a larger and grander scale. I believe the central use case is not collapse of society, but e.g. survival through the first few years of a nuclear world war, where not being exposed to radiation could be critical for the first few years.

Billionaires are very much part of the problem set because they are brought to top by system of ownership of property and productive assets. Their interest in prolonging the system, which is a problem because the system as such is not sustainable, and so it can't be sustained. Even the hoi polloi do this sort of stuff at small scale: saving for retirement via investing in stocks, speculating on bitcoin, or whatever; it is all attempting to create some kind of cushion of ownership of property, to later extract work and resources against their claims in some future time as needed. This is not likely to work in the long term, though, because future production capability will be less than it is today, and thus the large financial obligations must be satisfied from smaller production basis, meaning that something like the soft default via inflation at minimum is going to happen and eat away a big chunk of those obligations. In harder scenarios, there could be a global financial crash in some near future, created by destruction of asset bubble, dearth of energy reducing industrial output starting past peak oil (really: we should call it peak energy), and debt and inflation spiraling out of control as the productive basis of society reduces some 5-10 % every year, and we enter the degrowth era where each year people end up losing something like half decade's worth of gains at their purchasing power.

In fact, where I live, this has already started -- some 10 years worth of purchasing power has been lost in recent years, and economists keep predicting a recovery, but somehow it has repeatedly failed to materialize. Well, I think I know why -- collapse is driven by decreases in resources, and by increases in pollution, not money, which we can control and thus create or destroy at a rate we wish and where we wish, but modern politicians and economists appear to not consider these other factors in their predictions.