And yes, the kid who played C is a real life thug. He was sentenced a couple of years ago, hes a wanabe gangsters who fucked up his life. He could have gotten far with acting, he did a good job on the Sopranos.
Wasted talent.
Ironically, the "worst thing in life is wasted talent" is a phrase used by De Niro's character when he tries to talk sense into Calogero, like it was a predictment for the guy's future in real life.