In the modern post-war industrial era (1950-1980):
The excitement was in the actual economy of Main Street business. The giants of industry created businesses, built things, manufactured products, created innovation and originated internal domestic wealth in a fast-paced real economy. Natural peaks and economic valleys, as the GDP expanded and contracted, based on internal economic factors of labor, energy, monetary policy and regulation.
However, mid 1970’s bank regulators began issuing Glass–Steagall interpretations -that were upheld by courts- and permitted banks and their affiliates to engage in an increasing variety and amount of securities activities. After years of continual erosion of the Glass-Steagall firewall, eventually it disappeared.
This became the origin of the slow-motion explosion of investment banking. If you look back historically from today toward 1980 (ish) what you will find is this is also the ultimate fork where economic globalism began overtaking economic nationalism.
The second economy, which ultimately became the global economy, is also the Wall Street investment economy. Two divergent economies: Wall Street (paper), and Main Street (real).
The politicians became more valuable to the Wall Street team than the Main Street team, and Wall Street had deeper pockets because their economy was now larger.