Individualism regards the individual as a sovereign being (an end in oneself) with an inalienable right to life.
According to Philosopher Ayn Rand, “Individualism regards man—every man—as an independent, sovereign entity who possesses an inalienable right to his own life, a right derived from his nature as a rational being. Individualism holds that a civilized society, or any form of association, cooperation or peaceful coexistence among men, can be achieved only on the basis of the recognition of individual rights—and that a group, as such, has no rights other than the individual rights of its members.” 
The individual can gain immense values (such as knowledge and trade) by living with other men in society if that society is a proper society. A proper society is one where every individual holds as an absolute that every person is an end in themselves and that others are not one’s pawns, nor is one theirs.
Or, in the famous words of the hero of Atlas Shrugged, John Galt,
“I swear by my life and by my love of it — that I will never live for the sake of another man, nor ask another man to live for mine.” 
Such is the credo of the individualist — the independent mind — that recognizes no authority higher than its judgment of the truth.
Individualism is not opposed to living in society, so long as one is free from the initiation of force by others. Individualism is not opposed to one living in society as a trader; it is opposed to one living as a slave. Individualism holds that it is much better for a human being to live on a deserted island than to live in a society where one is nothing more than a serf ready to be sacrificed to the altar of the “public good.”
 Ayn Rand “Racism” The Virtue of Selfishness 129
 John Galt in Ayn Rand’s novel Atlas Shrugged