Another reason to start a firm

Good article from September's American Lawyer magazine regarding three African-American woman who all quit big firm life within their first five years to found their own firm...Ghatt Law Group. Their story tends to focus on the white male culture of larger law firms and the article points out that nearly three-quarters of minority woman associates leave their firms in the first five years. Additionally they say that "big-firm life was marked by a dearth of mentors and social networks."

Why do young lawyers want to work in large firms? The evidence seems to support the position that it's not a long-term gain...so are lawyers that short-sighted that they're only looking at those initial paychecks at the expense of long-term career development and wealth?