Considering that Fermi's argument is based on the plethora possibilities for evolution of intelligent life, I really doubt that EVERY SINGLE such life would have destroyed itself.
Of course not, but what kind of civilization would they be if they don't? Intelligent life doesn't necessarily have to have a technological civilization. They don't even have to have a social order like ours. I would think that a social system like ants or bees would be more likely to survive but would they be technological?
Going back to my theorized ways of colonizing it's possible earth was colonized like that by another civilization. Probably not because we haven't heard from them. There wouldn't be much point in doing that and not broadcasting EM like we do.
We evolved from predators which has a large effect on our social systems. If a civilization evolved from prey their social system would be different. They would probably be much more timid and paranoid and might not advertise their presence for fear of attracting predators. It is possible that type of civilization is more likely not to destroy themselves too. They might have been herd types which we aren't. A herd heritage might be better suited to survive. We weren't meant to be crowded and our society is suffering because of it. (and yes I've read Niven)