Having fewer competing dental offices around you is a good thing. But you also need to look at the population growth and the job availabilities in your area as well. When people don't have jobs, they are not going to go see the dentists....or they will elect to extract a tooth, instead of paying $2k to save it with RCT and crown. When people don't have jobs, they may leave your town for better job opportunity elsewhere. It's not a good thing when more people are leaving town. For example, dentists in Las Vegas used to make 2-3 times more than dentists in CA. When the economy tanked in 2008, a lot of people left towns and now dentists' incomes in Vegas are tie with dentists' incomes in CA.
When you practice in big cities, you are forced to try to be your best in order to compete againsts other dentists ie better care, better clinical skills, lower fees, accepting more insurance plans, working on weekends etc. Your great business and clinical skills help attract patients away from the less sucessfull dental offices around you. It's the survival of the fittest. People in big cities also care more about their appearances; therefore, they are more willing to pay for highly productive procedures such as implants, veneers, braces etc. High birthrate among Hispanics, large immigration wave from Asian countries, and job opportunities here in Southern Cal have helped my practices a lot.