> Then demographic trends fix it.
Demographics is the core thing that dooms all current forms of pensions, no matter if government, stonks or people just hoarding cash or other assets - in the end it's all fundamentally "IOUs" assuming that in 30, 40 years someone will be willing to trade that IOU from decades past into care. The one sole exception is real estate because a roof over the head doesn't need to be traded to be worth something for survival.
Up until now, this expectation has largely worked out over the millennia. People had ample children (by necessity), so there was always a healthy supply of working power to back the value of IOUs with work or consumables, old people plainly didn't live long (up until the 1800s, average life expectancy was barely 40!), and the young generation used to get at least some scraps of inheritance.
But at the moment, this is all broken across Western societies. People barely have children due to a number of factors (the pill, demands of employers, working too long hours, housing shortages, exploding costs of living, the economic and social poly-crises ever since 2001 9/11 ...) which will throw wrenches into the core promise of someone being there to trade the IOUs, old people live way too long (we're at about 80-ish years now) for any system to be sustainable because you can only get about 45 to 50 years worth of full-time working out of a human but they'll be living double that on the dime of society, and by the time my generation can hope to get some assistance in starting our families in form of inheritance we'll be long past the time where we could actually have used it.
Long term we're fucked, and I'd hope our governments show to be more deserving of our trust than tech and finance bros.