Many people will answer this question by describing how much they disliked their job, and wanted to be their own boss. I have a different take: I enjoyed my job, but I wanted to notch up to the next level. I wanted freedom to set my own schedule, get rid of the gatekeepers and have no upper limit to my income. I also started building this business during the evenings and weekends, testing the idea, before I left my position. That gave me both the funds and the proof-of-concept that I needed.