The older gentleman who was polite enough to listen to me said, "It's ok guy, if that 401k doesn't exist, then neither will you".
And so I think I will not stockpile any computers for later. I do like the engineering spirit of this however.
There are a number of ways that can not be true without a large scale societal collapse. Fraud involving pension funds has happened many times in the past (Bernie Madoff, Robert Maxwell being two high profile examples). The last financial crisis brought a bit more attention to the topic of counterparty risk - the idea that your "safe" investment is only as safe as the institutions that are backing it in many cases. It's not necessarily a high priority concern but I think it's worth at least considering splitting your retirement savings across more than one account with different institutions.
There are also lots of conceivable larger scale crises with historical precedent (many in the 20th Century) that would render your retirement savings largely worthless without leaving you dead. In many of those you would have more pressing concerns than your 401K but it still seems like not a bad idea to have some physical things of value that you keep somewhere secure but accessible (cash, perhaps gold and/or silver).
These concerns are all likely fairly low probability but there's certainly a whole range of possible scenarios between "my retirement funds are completely secure" and "I'm dead in a global thermonuclear apocalypse".
If someday the US looks like Syria, your 401k will be worthless but you’ll probably survive.
The first link on CollapseOS’s announcement called “Winter is Coming” has it all:
Think about a super volcano erupting, large meteor sticks, Black Plague style microorganism outbreak, a small or medium sized nuclear war, climate change lead global food shortages, late stage trade wars, and many more.