But what you're talking about isn't guaranteed. There's a lot of room between "stocks rip higher forever" and "societal collapse".
I'm not saying the right call is 100% t-bonds, but when you say things like "Over something like 30 years, the only question is whether your investment will outperform inflation or massively outperform it", you're making guarantees based on data from a narrow slice of history that is also the most economically favorable period just about ever.
Equities are the residual claim on assets, and their outperformance is predicated on growth. Economic growth comes from growing population and productivity. Neither of those is a given.
There's no world in which economic growth is low enough that 30 year bonds win out over equities, yet high enough that the US can afford to pay their debts in full without inflating them away. Economic growth isn't a given, sure, but there basically isn't a plan that works for that pessimistic of market conditions. If there isn't enough economic activity to support retiring a large majority of your generational cohort, then unless you save extraordinarily large amounts of money you simply don't get to retire.
I'm not saying the right call is 100% t-bonds, but when you say things like "Over something like 30 years, the only question is whether your investment will outperform inflation or massively outperform it", you're making guarantees based on data from a narrow slice of history that is also the most economically favorable period just about ever.
Equities are the residual claim on assets, and their outperformance is predicated on growth. Economic growth comes from growing population and productivity. Neither of those is a given.