Charlotte Street in New York City's South Bronx was once world famous for its blight. Now it's a slice of suburbia in the inner city - complete with Beemers and boats. More
That would be costs. Assuming an 8% annual return, if you invest in an actively managed fund with a 1.5% expense ratio vs. an index fund that charges 0.2% you'll give up almost 20% of your profits.