Earlier quoted context omitted.
Ummh - Index funds definitely do not have guaranteed returns.
There's "too big to fail" and network effects, can't let Bank of America or Boeing go bankrupt and wipe out shareholders, especially pension funds are major shareholders. There is so much government backstop going around that returns are certain. Compare that to bringing a new pharmaceutical compound into the clinic. The time from discovery to approval is ten years, with a billion spent over the lifetime of the proje…
Huge chunks of the indexes are now made up of a small handful of stocks, and as the stocks (FANNGS) go up so the indexes buy more, and guess what. They go up. And this will carry on, and on, until at some point a structural failure will occur. This may well be fraud, it may be government (not even the US government) intervention, it may be a supply chain failure or a market destruction. For example in November there may be a civil war in the USA... At that point the stocks will fall and if they fall disproportionately (which they will if the artificial pump that is floating them up turns off) then the indexes will unwind their positions... in fact they have to unwind. And this will glut the market, which will force more unwinding.
This is made worse by how the indexes actually track the market - you see, guess what! They (often) don't actually buy the stock! They trade synthetic securities over the movements of the stock with counterparties... and these counterparties never ever ever fail - they are solid players like investment banks, like Bear Stearns and Lehman Brothers, and Merrill Lynch and RBS. So - safe as houses.