Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Are stock index fund likely to keep being a reliable long-term investment option?
When you are putting your money in an index fund, you are not betting your performance against other asset classes but rather against competing investments withing the SAME asset class. The index fund always wins due to two factors: diversity, and lower cost.  The lower cost attribute is essentially where you get your performance edge over the longer run. That is why if you look at the universe of mutual funds (where you get your diversification), very few will have beaten the index, assuming they have survived. -Ralph Winters