Above all else, what makes our nation great is that it was founded on the principle of individualism. The fundamental precept that every individual has the inalienable right to life, liberty, and pursuit of happiness ensures that each one of us has the freedom to live our own life however we see fit, with minimal government intervention except to prevent us from infringing on the rights of others. The natural corollary of individual freedom is individual responsibility.
A society that values individuality assumes that individuals are responsible for their own lives, their own actions, and the rewards or consequences of whatever choices they make. Nobody is guaranteed anything but the freedom to carve out their own life and succeed or fail on their own merits. A society that places a high value on individualism encourages entrepreneurship, invention, and advances in all fields of endeavor by allowing individuals who develop and enable valuable innovations to reap the natural benefits of their imagination, enterprise, insight, and skill.
In a collectivist society, the right of the collective supercedes any rights an individual may have. The purpose of government is to ensure that all resources are equally allocated, and that nobody gets a greater share than anybody else. (It never works out that way in reality, but that’s the principle.) Individuality is suppressed in the interest of levelling, and good citizens must always be willing to sacrifice their individuality for the greater good of the collective.
A society that values the collective over the individual assumes that people are not capable of taking responsibility for their own lives, and that the government must assume the responsibility of making sure everybody’s welfare is provided for. Individuals who create more value do not reap the natural rewards of their efforts, but their profits are redistributed to those who can’t or don’t contribute as much. Collectivist societies work best with homogenous populations where people are considered essentially interchangeable. Uniqueness and diversity are not valued, and independence of thought and action are considered a potential threat to the welfare of the masses and the stability of the government.
Most nations lie somewhere in between the two ends of the spectrum. But our nation is the only nation that was explicitly founded on the principle of individual rights and dedicated to the preservation of individual freedoms. From my perspective, that’s what makes America the greatest nation on Earth.