You do not become a dissident just because you decide one day to take up this most unusual career. You are thrown into it by your personal sense of responsibility, combined with a complex set of external circumstances. You are cast out of the existing structures and placed in a position of conflict with them. It begins as an attempt to do your work well, and ends with being branded an enemy of society.
The dissident does not operate in the realm of genuine power at all.
He is not seeking power. He has no desire for office and does not gather votes. He does not attempt to charm the public, he offers nothing and promises nothing. He can offer, if anything, only his own skin -- and he offers it solely because he has no other way of affirming the truth he stands for. His actions simply articulate his dignity as a citizen, regardless of the cost.
There were no dissidents then in the USSR because they were all killed.
A lot of us don't want to be quite that serious about world problems.
Our life is there to enjoy, not to be an eternal dissident, eternally unhappy with how things are and with the state of mankind.