4% is probably a reasonable rate given current market interest rates for a debt you expect to be paid back. We are in the middle of an epic central bank created

4% is probably a reasonable rate given current market interest rates for a debt you expect to be paid back. We are in the middle of an epic central bank created bubble for debt securities. Rates have never been this low. 4% is nowhere near a reasonable average rate over the period concerned. In the 70's, the yields on US Treasuries were in 10% range. As late as the early 1990s commercial real estate loans backed by good collateral were in the high single digits. What seems like a small difference in rates can easily make an order of magnitude difference over a 40-50 year period.