Immune to market fluctuations. Based on years working and salary so if you worked a long time then retired and lived for a long time you may get more money than if you had a bag of cash in the market. It lasts until you die and your spouse can inherit it so it provides stability for you and your partner for the rest of your lives instead of having to guess how many more years you’re going to live and dividing your savings by number of years left. Removes that stress of outliving your guess and running out of cash.