1 small guy changing stuff is basically impossible. But 100 million small folk sufficiently annoyed with something changes a government (for better and for worse), whilst having basically zero influence over a corporation (they're not the customer, they don't have enough buying power for a hostile takeover, they certainly don't have the wherewithal to destroy them by launching a competitor... which they probably don't even want to if they think what the corporation does is bad). The exception, of course, is that if the corporation bothers that many small people that much, a government might get around to listening to the small people's arguments more than the corporation's.