I think in the western world, many would argue an S&P500 index fund held in a vanguard account would do what you said. It’ll generally hold its value, is accessible via a phone call to broker or a computer and password (sell some shares and withdraw cash from an atm anywhere in the world), and you probably won’t get rugged.
Sure it will have fluctuations in value and you could get rugged by the US government and/or broker, but the odds of that seem quite low (maybe as low as the US trying to ban bitcoin).
I personally believe Bitcoin has the best characteristics AND also huge asymmetry which is why I hold it, but just trying to steelman why a boomer would and probably can be satisfied with his ‘diversified’ equity portfolio, at least for the remaining few decades of his life.