What mistake does author make when he tries to do business in the bank why does he do so?

The author makes the mistake of underestimating the complexities of banking operations and the regulatory environment, leading him to overlook essential details in his business strategy. He is driven by the desire to succeed and capitalize on perceived opportunities, but his lack of experience and understanding of the industry results in poor decision-making. This oversight highlights the importance of thorough research and expertise when entering a highly regulated sector like banking. Ultimately, his ambition blinds him to the critical factors that govern successful business practices in this field.