What is one reason people often under-save for retirement?

One reason people often under-save for retirement is the belief that Social Security is sufficient to cover their living expenses in retirement. Many individuals assume that the benefits provided by Social Security will be enough to sustain their desired lifestyle or to cover all necessary expenses once they stop working. This belief can lead to complacency regarding personal savings and investments, as individuals may feel that relying on Social Security will be sufficient for their financial needs.

However, Social Security benefits typically replace only a portion of pre-retirement income—often around 40% for average earners—leaving a significant gap that personal savings, pensions, and other forms of retirement income need to fill. This gap can lead to financial strain in retirement if individuals haven't adequately prepared through personal savings and other investments, reinforcing the importance of comprehensive retirement planning beyond just relying on government-provided benefits.