Doing that reliably over a meaningful period of time is the problem. In my book (from the perspective of an investor) you'd need to "outperform?" the index to cover the costs of frequent trades and potential losses at no actual cost to the investor.

It says replicate, not outperform.

Just buy the Vanguard index fund.

It's easy to replicate the returns on the index, you just use the dividends to pay the fees, since the S&P500 index includes only capital gains only and is not "Total Return" (include capital gains plus dividend).