There are a bunch of hypotheses about why we have yet to encounter or discover other intelligent life in our galaxy/universe (or, more specifically, the Fermi Paradox). Two seem particularly relevant here:
(a) 'It is the nature of intelligent life to destroy itself': There is some period of technological development where the odds of self-extinction become extremely high (e.g. the relatively recent development of nuclear weapons... for example...).
(b) 'It is the nature of super intelligent life to destroy others': Intelligent species past a certain point of technological capability will destroy other intelligent species as they emerge. A species might undertake such extermination out of expansionist motives or even just rational and prudent self-interest: an intelligent species that has overcome its own self-destructive tendencies might view other advanced species as a potential threat. A highly advanced alien species would also likely be a super-predator (as are humans).
But lately I began wondering how much of it is survivor bias and thinking that we cannot extrapolate this into the future.
Our human civilization is very young. Our governments sometimes resort to the level of discourse more appropriate for 5 year old boys fighting in a sandbox. But apparently some toys look dangerous enough to be put on the shelf and never touched without adult supervision.