A Richer RetirementPraise for A RICHER RETIREMENT Bill Bengen has delivered a tour de force of retirement planning. Although written for retail clients, financial advisors and other professionals will benefit from his analysis of the most difficult problem facing retirement planners: how to make ones nest egg last a lifetime. Bengen has quantified the elements and risks underlying how much retirees can spend over a 30 year (or sometimes longer) retirement horizon.