Both capitalist and socialist economic systems are Ponzi schemes.
Pius XI,
Quadragesimo anno (1931)
In the first place, it is obvious that not only is wealth concentrated in our times but an immense power and despotic economic dictatorship is consolidated in the hands of a few, who often are not owners but only the trustees and managing directors of invested funds which they administer according to their own arbitrary will and pleasure.
Basically, usury makes the stock market "profitable".