From reading all these threads there's clearly a large number of software developers on HN who can easily set up complex infrastructure and make it provably 100% bug and exploit free. Weird that they aren't all billionaires from selling these skills though.
Being a billionaire has very little to do with engineering talent.
Unplugging the internet is easy. Running high risk code offline in highly tamper evident ways is hard, but plenty of teams like mine specialize in this sort of thing. (See: https://distrust.co and https://caution.co)
In our audits we regularly see billions of dollars in value at major companies at risk of theft by any anon paying attention that wants it, and we also absolutely know how to fix it and we maintain a lot of open source tools to accelerate doing so.
Some simply have no interest in any fixes that are not legally required or might have any short term impact on team velocity.
Survivors bias is a hell of a drug.