You will want to re-read Chapter Seven of this great novel, as this chapter details the way in which Bryon changes thanks to his serious relationship with Cathy and the way in which he becomes much more aware of his position in life and seeks to change it to become more respectable. Consider what Bryon tells us:
I got a job in a supermarket and I did a pretty good job of changing my attitude, outwardly at least. I couldn't help thinking smart-aleck things, but I could help saying them. Sacking groceries wasn't the most fun job in the world, but I was bringing in money.
This money was needed by Bryon's mother, but this also represents Bryon's maturity from the kind of character who we meet at the beginning of the book into a character who recognises that there is no future in pool hustling and not being respectable. Thus Bryon begins to transform himself to try to give himself some sort of hope of a future and also to improve his own social standing, even going as far as to bite back the comments he would like to make but now recognises are not appropriate.
It is also socioeconomics that come into play with Bryon in a different way, as he notices that Mark is earning a lot of money and begins to wonder where this money is coming from. At first he assumes Mark is winning this money by playing poker, but his discovery of the real source of this money is what leads to the story's tragic ending.