The main point here is that while keeping all your savings in very low-risk but also low-returning investments might make you feel safe and secure now, you could be opening yourself up to the bigger risk that your nest egg may not be able to support you over the long term.
The reason is that bank money-market accounts or CDs alone might not provide the returns you'll need after inflation and taxes to maintain your purchasing power throughout a post-career life that, as this longevity tool shows, could last well into your 90s. Which means that to avoid having your standard of living slip over a long retirement, you really ought to consider investing at least some of your savings in a diversified portfolio of stock and bond funds.
Many retirees limit their stock holdings to somewhere between 40% and 60% of their overall portfolio. But others may decide to go with a higher percentage, or a lower one. You can get a sense of what blend of stocks and bonds may be right for you by completing Vanguard's risk tolerance-asset allocation questionnaire. Besides suggesting a stocks-bonds mix, this tool will also show you how different mixes of stocks and bonds have performed in different market conditions.
Learn more about this by reading the article written by Walter Updegrave at CNNMoney http://money.cnn.com/2017/11/09/retirement/investing-safety/index.html