One shouldn't automatically assign probabilities. We can't really say how likely it is for life to develop on any given planet, on average. Maybe it's so low that we are the only planet with any form of life anywhere.

On the other hand, one shouldn't assume that all extraterrestrial civilizations would lack the means or inclination to contact us.

A small percentage of "contacts" have not been discredited or explained. This does not by any means imply that these were genuine alien sightings. It's just a reminder that there are no certainties here.