These billionaire nerds got lucky, but now think themselves as natural-born leaders — as evidenced by their wealth, but they wouldn't survive the post apocalypse.
If society collapses, and you were an elite ex-special forces armed detail on a billionaire's security team, would you continue to accept their now-worthless dollars, or would you or just take a fully-stocked bunker for you and yours?
Remember there are effectively no cops or courts in this world that would stand in the way of the (former) billionaires from being demoted to farm-hand by those with the guns.
Consequences from the aforementioned functioning society that would have collapsed in the billionaire's dystopian survival fantasy.
Also, soldiers running amok in rhe absence of a strong government happens in our world - ask any civilian who's been caught up in an insurgency, or look at places like the Democratic Republic of Congo where armed militias run fiefs, and you have to pay tribute to operate a cobalt or lithium mine "their" area.
It seems a lot of the bunkerbros don't realize this value of society. They don't need society any more, they think.