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.

This is really underappreciated. I'm a big fan of diversification, and it can be very important to lower your risk-appetite if you're relying on your investment income in a short-medium timeframe (e.g. if you're planning on retiring in 5 years, being all-in equity is just silly, or if you're saving for a downpayment on a home in a few years, stock investing isn't the primary instrument to use), but in the long-term (e.g. a 25 year old thinking about early retirement someday) it just doesn't make sense to take too little risk.

And in part it's precisely because of the worst case scenario happens where worldwide stocks don't outperform treasury bonds, you're likely living in a world where your money isn't legal tender anymore anyway, and any stock/bond investment decision you ever made basically irrelevant.

So if decisions regarding the extreme downside risk are irrelevant, you might as well optimize for the upside.

How did the Russian stock market do? I'm curious and haven't heard this discussed before.