Are you asking how does money effect someone's decision making process? That's a question only that person can answer. Everyone's different to a degree. I believe AJ quit because he knew something was wrong with him (He kept asking his corner What's wrong with me?) He also knew he had a rematch clause.
He probably saw one too many fights on tv watched Rocky too many times and thought he could handle it. Probably went to a gym ran by morons and this was the result.