Fees
According to a May 2014 WSJ article, after 30 years, a $200,000 mutual fund investment (8% gross annualized return) grows to $1.4 million after paying the typical mutual fund annual fee of 1.25%. This was the average expense ratio for mutual funds for 2013 (source: Morningstar). The same investment grew to $2.0 million if annualized returns were the same but a 0.04% annual expense ratio (source: ETF.com).