Yes, a country's development depends solely on its politicians, because the politicians are the ones that put the laws in place that allow a country to flourish. Without private property rights, and country will not be sound. People in the country will not be able to do their work. Politicians are responsible for making sure good laws are in place.
A country's development does not depend solely on politicians. While our politicians and government have a significant affect on our development, a more significant factor is the people. We the people are the ones who inherently grant these politicians power, and if we are to truly advance as a society, it must start with the citizens.