Why does Craig get fired from his job?

One of the instigating moments that triggers the later events in the twisted, dark thriller Cheap Thrills, is the protagonist, Craig Daniels losing his job.

Craig has the ambition to be a writer but to make ends meet works for his father in law at a car repair shop. But he loses his job early in the movie and is threatened with eviction from the flat he shares with his wife and young child. His despair at this prospect drives him to be willing to risk a great deal when offered an increasingly bizarre and increasingly dangerous series of wagers while drinking in a bar with a old friend.

The movie doesn't give us a lot of backstory to explain this, leaping quickly onto the main action. But the loss of his job seems a critical moment. Why did he lose his job (and does the reason explain anything that happens later)?