There are three possibilities: (1) banks created it, (2) their activities caused the economy to grow faster than it otherwise would have, and they reaped the benefit of that extra growth, or (3) it was somehow skimmed away from the rest of society. Possibility #1 is unlikely: banks certainly created mountains of debt, but mountains of money would show in skyrocketing monetary aggregates and high inflation, neither of which happened. Possibility #2 also seems unlikely. There’s simply no evidence, either in comparisons over time or comparisons between countries, that economic growth over the past two or three decades has benefited from financial rocket science. So that leaves possibility #3: somehow, all this financial engineering was based on skimming money away from everyone else.
Gute Frage. Und der Versuch einer Antwort. Wer sich für die Materie interessiert sollte unbedingt auch die Kommentare unterm Original durchackern.