"Where is the money coming from? "

Profitable companies. This is incredibly obvious. It is where dividends come from already.

You keep mentioning social security but it isn't comparable as it has a relatively low income cap on payroll taxes and raising this easily makes it solvent.

What is actually frustrating is the wealth of the richest 400 people in the US now equals 20% of GDP. In 1982 it was only 2%. THE MONEY IS THERE!