But I am intrigued as to who's a 'veteran', what defines them,
Veteran status is mostly based purely on tenure, with a helping of social status. Veterans are a fixture of the community because they appear frequently and have done so for longer than most. Such a person tends to be respected, unless they act in ways that compel disrespect. Simply being consistently present and socially innocuous is enough.
and how they actually 'shape the culture'.
Veterans shape culture because newcomers see them as models. "Culture" is no more than
the common values and accepted patterns of behavior in a group, so anybody that has long tenure and/or significant respect in a group can be expected to exemplify that culture. If they didn't, social friction and loss of respect from others would either have pushed them out or relegated them to lowly hanger-on status already. Newcomers, on social high-alert as they try to find their place in the new group, are incredibly sensitive to these things.
Because of that intense regard, veterans do not need to *try* to shape culture. On account of their status,
everything that they do is an expression of the group's culture, which newcomers will then follow (or at least take pains not to antagonize).
In the modern world of social media, I think everyone understands that whatever you put on the internet exists forever and will be endlessly scrutinized by people with any interest in you. What I think fewer people reflect upon is that this is not actually a significant change from how social groups have always worked. Constant scrutiny in public has ALWAYS been the rule--the only things that social media has changed are the scale of visibility and the durability of memory. It has always been the case that some number of people are always watching you, and are subtly shifting their thinking and behavior in response to yours. Especially if they hold you in extremely high or extremely low regard.
Are they attempting to 'pay forward', but with conditions attached?
I think there are several patterns in play.
Most veterans, I think, either do not understand or seldom think about the fact that they are influential. After all, they have no title and no special skills--they are just another person out dancing, unchanged for the last decade! So they just
do stuff, for their own private reasons, and do not consider the wider implications of the example they are setting.
Some veterans understand their position, and are intentional about the model they set. These are the leaders that we respect, although we may not agree with their views or goals.
Some folks who are not yet veterans also understand this dynamic, and try to project influence that they have not yet earned. Some get away with it, especially if they are charismatic; these are the "successful upstarts" that frequently annoy tenured veterans. Others do not; these are the "blowhards" or ones that "don't play well with others," and they generally get dismissed and sidelined over time.