Well look at it this way. Tony Montana started out as a likable character. Comes to the States to get away from Castro, works as a cook and dishwasher with his best friend Manny and eventually work their way into the gangster scene. After awhile it starts getting into the head of Tony after working with Sosa and working his way to the top.

Then it all comes crashing down once it gets into his head too much and eventually everything spirals out of control, include him losing his wife and killing his sister and best friend, all because they were sleeping together and about to be married. Why? Because Tony didn't like the idea of his sister sleeping with someone.

Now picture that as a Nice Guy, at first they seem like a likable person because they're being nice, who doesn't like that? But as they get more and more comfortable, they start to show their true selves, much like Tony Montana and in the end they get all pissy when the girl they want sleeps with other people. Now Tony didn't want his sister, but they share the same mentality of the woman sleeping with someone else.

So in a sense, I guess you can say Tony and Nice Guys are on that same kind of level, mentality wise.