> If everyone put money into an index fund that guarantees returns, what is the difference between that and a Ponzi scheme? No index fund guarantees returns, s

> If everyone put money into an index fund that guarantees returns, what is the difference between that and a Ponzi scheme? No index fund guarantees returns, so the question is a non-sequitur. With regard to the question of how does the fund keep value -- the fund holds the equities that are in the index. The equity prices rise and fall with the market, which is hopefully based on the fundamental discounted future value of all cash flows from the company.