Inflation and opportunity costs are disadvantages of holding cash. Even if the cash is invested in a very safe asset, like money market funds, CDs, or short-term treasuries, there is a risk that inflation exceeds short-term interest rates. Otherwise, savers face massive opportunity cost. 200 years of history shows that stocks are by far the most productive liquid asset class, returning a fairly stable average of about 6.5% per year after accounting for inflation. A well-selected portfolio of stocks can return much more by far.