The average joint retirement at age 62 or older is 30 years. In the long run - and that's the only rational way to invest - the only sane definition of money is purchasing power. Money loses some of its purchasing power every day because of inflation, so every time our cost of living doubles we will have, by definition, lost half our money.
For answers, let's look at history. Since World War II consumer prices are 13 times higher than they were in 1945. The equity market today stands more than 70 times higher than it did in 1945. Dividends are 40 times higher than they were in 1945. In general I would rather be an owner of companies rather than a lender to them. And I believe that long-term optimism is the only long-term realism, especially at the present moment.