Inconsistency On Jack Kerouac's On The Road

Hi,

I am reading Kerouac's On The Road book. At part 1. Chapter 5 we read that, Sal had only 7 dollars left and spends all his money at the bar with Slim. However in the morning he had a modest breakfast. And also in the following pages he buys a milkshake. How could that happen? Where does that money come from? Am I missing something here? That kind of inconsistency makes me sad and I do not want to continue reading that wonderful book anymore. Please share your thoughts about that. Am i making a mistake?

Thank you for reading