Why? Because there isn't sufficient evidence to support life outside of earth and its atmosphere. Even though there is a small chance of finding anything, that doesn't mean nothing is out there, and it doesn't mean we won't ever find life beyond earth. A recent study predicts that there are about 160 billion planets in the Milky Way. Just the Milky Way. So plug that into the Drake equation and see it's still possible.
But again, most people and the press say there isn't found life yet because, well, there really hasn't. And on a day-to-day basis, ordinary people don't worry about it.