It is disheartening that you realized this only after getting involved in activism. I think that in itself is a more significant indication of how hopeless the situation in America is. It underlines the main reason why serious social change is so difficult.
Put it simply: the government exists to protect the interests of corporations and wealthy people. Dissent of any kind challenges the status quo and therefore must be discouraged and quelled by any means necessary. The rights of "The People" (i.e. the poor) mean jack shit, because The People only exist to make the rich richer. This has been the case since the country's founding.
This is not to say that change is impossible. But, historically, the only time meaningful change has happened is when there was overwhelming social pressure. We aren't talking about petty (and for the most part meaningless) activism here and there. We're talking about social dissent of such magnitude that it threatens to become a revolution. Only in such times has the establishment allowed any sort of concession.