Dennis was born in California and attended the University of California at Los Angeles where he majored in Economics. He left UCLA in his junior year, impatient to begin a career. He first enlisted in the USMC to satisfy his country’s service requirement. Upon the end of his military service, Dennis embarked on his business career, starting with IBM. Many years later, in 2006, Dennis relocated to Dallas, Texas when he took over as Chairman and CEO of a public company headquartered there.