Savings sometimes earn low returns or worse. Consider that the S&P 500 is about where it was in spring of 2000, so if you bought and held an S&P 500 index fund for 12 years, then you didn't even keep up with inflation: no capital gains and about a 2% annual return from dividends. (For additional bleakness, recall that dividends are taxed.) Karl Smith:

We sometimes think that the large projected budget deficits and lack of savings on the part of middle aged Americans represent a failure to accumulate enough assets to pay for our own retirement and hence an increased burden for our children.

However, they are simply one manifestation of a much deeper issue: with slowing population growth the world is running short of things to own.

Demography isn't exactly destiny, but Table 2 here doesn't make me optimistic about the stock market. (But you can still get lucky. No one who bought AAPL at $350/share last year and sold it at $600 this year is complaining about low dividend returns.)
More Smith:

Far from being a utopian ideal to which we should all strive, savings is actually logistically difficult. Things rot. The wear out. The become obsolete.

You have to pay to save, and I know because it is a payment I have had to endure. You can loan your money to someone though outside of official channels getting it back is a non-trivial exercise.

People can and do [lose] your money.

This is actually more common than people stealing your money. Most people will lose your money out of stupidity.

...All of this comes to the point that in an aging industrialized country that [is] already really dense savings because really difficult. Nonetheless people are still programed that its an unmitigated good.