Yes and No. You can sell principal but that will decrease the next interest payment. The 30yr treasury example was just a baseline, and part of my "never invest in a fixed annuity" sales pitch. It is pretty easy to see the problems inflation and time create. This is why I suggest people build the quick and simple model and play with the numbers. It helps them create a budget for 5yr, 10yr, 15yr, etc and think about the future. One thing is for sure, the future will be different than today. Retirement advice has changed greatly over the last 40yrs.