How to think better about long-term budgetary issues? Maybe define a couple of simple financial functions. Let A = assets ($), I = income ($/year), and S = spending ($/year). Then:

• Burn Rate = A/(S-I) — the number of years it will take to deplete all resources
• Breakeven Point = (S-I)/S — the fractional cutback in spending to stabilize cash flow

Thus, one might estimate, "We can keep spending at our current rate for 5 years, after which we will have to cut back to 80%." That puts things into a more useful perspective, and clarifies the timescale and amount of thrift needed during temporary tough times. It doesn't consider changes over time in price levels, varying tax brackets, interest rates, etc — but for most purposes, in ordinary circumstances it gets into the right ballpark. Useful!

_{(cf Money, Mechanism, Meaning (2001-02-15), Money Wisdom (2001-05-20), No Retrenchment (2002-08-25), Improving Trend (2010-02-08), Shiller Price Earnings Ratio (2021-03-29), Harry Browne Rules of Financial Safety (2019-12-24), ...) - ^z - 2023-11-15}