In the famous GoodFellas book by Robert Ludlum, the main character played by Al Pacino, Jimmy "Goodfella" Luciano, is a tip-top thief. However, in real life, I can't imagine such a book becoming a movie. This is mainly because it is very "movie like", and people just aren't in love with that aspect of the book, or film.
There are two types of violence in the book, or film. The first one is the stuff that some people think is too over the top and is 'unfilmable'. The second one is the part that everyone in the audience finds interesting and endearing.
For example, The Godfather movie with Michael Corleone was like watching reality television shows and entertainment news. It was just too outrageous to be possible to make a movie of. Yet, the men that were "in" loved it.
The reason why GoodFellas is a movie, is because it has a lot of stuff that happens out of sequence. The audience is not meant to have time to stop and "get it all", it's too quick. This is why most movies don't work as movies.
In real life, if a man is really successful, and he's in charge of a bunch of people, they will find ways to get the job done without having to do all the dirty work. GoodFellas doesn't have all the money or the people to do that, so he ends up hiring a hit man, just like in any other action flick. It's a way for the story to move along.
In the book, the bad guy ends up being "Goodfellas" Joe Friday, the head of the Cleveland mob. It's okay to have him use a hit man once in a while, but the rest of the book is all about how people learn to get around them, and escape from their grip.
In the movie, the bad guy is Mr. Big, who is sort of like the rich old guy who everyone wants to take down. Once again, the point of the movie is that they are evil, and it's not okay to do anything to them. While it's entertaining for some people, they just don't want to see these types of movies.
If someone wanted to make a movie about the people of The Godfather that was a fake, this would be a good one to watch. But I'm sure people will be waiting a long time for a movie about the living, breathing people of The Goodfellas.