Oh go on then. It's really not that interesting. However it does sort of overlap into the nonsense that Sadken and El Jefe are bickering about.
Gangsters represent independent working class maleness. They have re-appropriated the state's monopoly on coercion. They are either a sort of one man/one familiy revolution - or they are would be aristocrats, using the time-honoured techniques to gain a fiefdom of violence, sharp business practice, co-opting of local police/militia/magistrates (depending on your era).
They are natural working class heroes for this reason, and for the fact that they are a source of employment, access to credit and access to illegal vices. They are, of course, as exploitative as any other business or state enterprise - but you know them, can theoretically reason with them. You are close to a centre of power and decision in the way working class people can never be in a state or political institution. This proximity to a centre of power and decision is why so many fringe left groups exist. As actual political entities they are preposterous - but if they get too large then people get divorced from the leaders and decision makers and don't want to play any more.