Shares are the most profitable investment in the long run.
According to the results of a survey from 2015 (Future of Investors (2005), With Updates to 2015), investments in shares proved to be the investments achieving highest return:
Total return of different investment classes for the period from January 1802 to June 2015
Source: Siegel, Jeremy, Future of Investors (2005), With Updates to 2015.
Explanations to the Figure:
Total return: all income from individual investment classes (shares, bonds, treasury bills, gold, and USD), such as realized capital gains, dividends, and interest, is immediately reinvested and re-accrued further throughout the period.
Real return on each investment class takes into account the gross return less inflation.
Yields on shares: Despite the huge economic, social, and political changes of the last two centuries, shares have achieved stable growth over this period, averaging 6.7% per year. From USD 1 invested in shares in 1802 (taking into account the reinvestment of all paid-out returns), by 2015 1,050,085 USD was created.
Gold: Figure 1 shows that gold only maintains its value in the long run, and in the short term even greater value drops are possible for gold than for shares. Investments in gold in the interim also do not bring any payments, as is the case for shares (dividends) or bonds and deposits (interest).