> Average market growth is higher than the average inflation per year. I trust that investing in the market and holding a percent of your portfolio in Treasury bonds will give you a very good chance of growing or maintaining your savings against inflation and market variance.

There are several problems with this analysis;

1) You're making a 50+ year forecast (depending on your age) based on a 100 year data, a prediction ultimately not based on first principles.

2) Ultimately average inflation doesn't matter; the specific things you'll need to buy matter. You can enjoy the lowest CPIs in the world and still get shortchanged if you need to buy a house in the Bay Area at the end of a boom.

3) Lifetime averages might look good, but not all years of your life has the same wealth sensitivity; e.g you can postpone getting into a mortgage in your 30s but can't really postpone unexpected healthcare costs after 50s without lifespan altering consequences. The aim is not maximizing your returns until the day you die, it is to have enough when you need it throughout your life.

I'm not saying you're going to be necessarily wrong, but there is a risk of overemphasizing the predictive power of past performance and understating outlier events.

By the way, economies can fail in more than one way, e.g. markets can't really beat hyperinflation, which is a salient risk today depending on how covid shapes supply/demand curves, and in stagflation markets would suffer in addition to inflation, which is an outlier risk but a risk nonetheless. Sure, any of these would resolve in a decade, but during that decade you're going to be faced with purchasing decisions that you can't wait out, hence the melting of your ice cube.