Dr. William Bernstein is noted in some circles as a "contrarian". His principle: "once you have won the game, why keep playing?" is derided by some who view investing in laddered CDs as effectively "dead money". Bernstein's logic, supported by Zvi Bodie, is analyzed in this easy-to-read article appearing a while back.
Avoiding the Worst Retirement Investing Mistake - Go To Retirement
Bottom line: once you have amassed an income stream sufficient for your projected retirement needs, adjusting for expected inflation, there is no logical reason to keep "playing the game" in the stock market. I would also add the bond market.
Harvest your gains and principal to enable you to meet obligations you project for retirement. Invest those in a ladder of CDs (preferably a ladder of five-year CDs). Invest what's left over in the market, as you see fit. Keep a healthy contingency fund for emergencies. Should advanced age deal you a bad deck, fall back on your contingency fund and/or market investments.