An image is worth a thousand words:
From Washington's Blog (a right-wing albeit interesting site).
The graph, which I believe refers only to the USA but should not be too different for Europe and maybe other places, clearly illustrates on what was based the social stability and prosperity of the mid century (besides colonialism and neocolonialism, that also): the oligarchy accepted to share and contain their greed.
Why would they do that? Because of the USSR contagion menace, which in fact was diverted to the so-called Third World, where such concessions were almost never made and instead was intensively exploited to compensate. At the time unions and the worker movement was strong enough that it had to be neutralized... until Margaret Thatcher and her American acolyte, Ronald Reagan, arrived to scene. Also the memory of the Great Depression and its uncontrollable consequences was very vivid. Keynesianism was fashionable.
Then the system began to be dismantled and wild uncontrolled credit served as cushion for some time, probably more than initially expected.