This rapid increase in the supply of almost costless equity capital seems to have been driven by the conviction that returns from some of the new technologies would be enormous for their producers and, dispersed across the US economy, their users in terms of productivity.
The financial services sector provided the machinery for all this to happen, itself using the improvements in information and communications technology to lower its costs. Up to a point, this was a model of what the financial sector is supposed to do: allocate capital, and by seeking out the highest returns, maximise the growth potential of the economy.