Gangster (n.): A rich boyfriend, but a poor husband.
Many women are attracted by pretty things, money and power. A man with the brutality to seize these from others can exert a strong attraction on women. However, women also want legitimacy, for themselves and their children. They may date a gangster, but they want to marry an honest man. Men who cannot either conform to society, or build a society that conforms to them, will find their only company to be hustlers and hookers.