Partly due to his leadership, it has defeated all serious challenges to its way of life. Even the worst despots pay lip service to it tenets. It has prevailed in part because of its ability to satisfy the material needs of its citizens.
If Roosevelt was incorrect about the origins of the Great Depression, why has the welfare state survived? First, Roosevelt was successful in changing people's expectations toward government. Government became not the enemy of liberty but the guarantor of people's economic rights. When problems arise, many expect the government to solve them. Second, once a program is initiated, it develops its own constituency, making its elimination--or even substantial cutbacks--extremely difficult. Finally, the very wealth created by the free-market system makes overt poverty in any segment of society unacceptable to most Americans. There is a broad consensus that providing some sort of a social safety net is a fundamental task of government.
Despite having been proven wrong about the weakness of the free market, Roosevelt would no doubt be pleased to look back on the years since the Great Depression. Democracy has flourished, there is no "paternalistic system" that guides the economy. Yet, the harsher aspects of capitalism have been softened. Few citizens are ill clothed, ill housed, or ill fed. The government is much stronger than it once was, and therefore is more able to meet any future crises that might befall the nation. And the presidency that Roosevelt helped establish is the center of the country's political life.