Yes and no. Yes, capitalism enshrines rational self-interest. No, you are completely off the mark when you claim that to act in one’s own benefit, that is to act selfishly, is evil.
To be selfish means to look out for one’s own interests, i.e. one’s own life. To eat to support your life is selfish. To make love to the woman you love is selfish. To have pride in ones accomplishments and character is selfish. To use one’s mind in the pursuit of ones own happiness is selfish. By what standard can one judge these selfish things as evil? Only by an irrational one.
Man’s life is the standard of value. All that supports a man’s life is good, and all that destroys man’s life is evil.
If evil is that which destroys man’s life — and to look after one’s self interest — is to support one’s life, then how can selfishness be rationally held to be evil? It cannot.
Capitalism is not opposed to an individual living in a society, so long as he is free from the initiation of force by others.