Did you read the article and the link to the longer (origional) one on which Milton Friedman commented?
Of course, there's no such thing as a sure thing. Who would expect that (other than one of the DemocRAT party's constituants)? One could immediately write off any person as a nit-wit who would not add the prudent caveat that the past isn't a guarantee of the future. Even in a horse race, "past performance" is an indicator of "future performance" barring any inforseen difficulties/problems.
Thanks for your comments.
Those who consider investing in an index of, say, 100, 500 or 5,000 top US companies to be risky, never say where, should those companies fail, the money to pay Social Security taxes and benefits will come from.