Ego can be not only individual but also collective. Leo Gura, from whom I've been learning and influenced more than any other nondual master except for some Chabad rabbis, defines it as "an irrational self-preservation instinct".
Souls of human beings are coupled with their respective individual egos when they descend to this world, borrowing physical bodies. Our bodies can't survive as purely spiritual beings with no ego.
Any (sufficiently complicated) social collective or system also has an ego known as collective ego. Social collectives can vary from larg-scale ones such as nations to small-scale ones such as families. Culture in the sense of a set of unspoken rules is how the collective ego of a nation and or a state manifests itself.
It may be difficult for you to imagine how social systems can have their respective collective egos. For example, human languages have their collective egos, which are known as normative grammars.
Just as human thought, speech and action can be better understood through the lens of the ego, so can social collectives be. I'd like to briefly demonstrate how collective egos operate in two social collectives in which I was an insider for about 30 years - Esperanto movement and academia.
These two social collectives are especially useful to understand the nature of collective egos simply because few people would imagine, at least if they only think naively, that their collective egos are far more problematic than they seem at first glance because of their superiority complex, which is parallel to the so-called spiritual ego of individuals. And this is one of the main reasons why I've decided to leave both of them after I encountered Chabad Chassidus and other teachings of nonduality and woke up.
The Esperanto movement and academia are similar to each other in that both of them are cult-like and have dogmas, which are not perceived by their respective members as problematic. I wish I were wrong, but having spent about 30 years in both social collectives, I'm quite sure that many of their members seem to believe blindly that their respective social collectives are superior to other language movements and occupations respectively. If this is the case, this very blind faith is nothing but an illusion of their collective egos, which makes their members believe this way to preserve themselves.
Many people who first get acquanited with the idea of Esperanto may be impressed with its "nobleness". But upon closer examination you'll realize that it's not necessarily superior to other ideologies promoting specific ethnic languages as a means of international communication to unify the mankind. The problem is not so far with what language to use for this purpose but the very fact that a specific language is perceived as a possible - or for most Esperantists the best - solution. You have to transcend language for this purpose. They are stuck instead at the same level of consciousness that is causing this problem.
Academia has a set of far more elaborate (and toxic) rules that are imposed explicitly and mostly implicitly upon its members by its collective ego. This toxicity infects the individual egos of many of these members. How does this infection manifest itself most prominently? This collective ego bloats their individual egos. For many of these with bloated egos the happiest moment in life is when they have their papers-shmapers quoted by their fellow in "peer-reviewed" journals. This very institution of peer reviewing their "holy temple" and peer reviewers and its "high priests". I can easily recognize people with bloated egos not only in their speech and action but even in their external appearances, especially in their facial expressions.
PS: I strongly recommend everyone to listen to a two-hour-long online lecture entitled Collective Ego by Leo Gura. I've even listend to it several times.