One concept that people often miss when structuring groups, organizations, or social spaces is the importance of those who aren't here. People who aren't actively present can be just as important for the medium- and long-term future of your project as those who happen to be around right now (sometimes more so!) -- and if you overfit your planning to the people who happen to be around right now, you may end up damaging your long-term prospects.

Here are some examples of what this can look like:

1. A king falls into decadence and surrounds himself with flattering courtiers. Whenever he wonders whether things are going in the right direction, the courtiers assure him everything is grand and maneuver to prevent him from learning about any negative developments.
2. An online community is meant to represent a wide range of viewpoints and perspectives, but biases in moderation begin to creep in that drive some away. Since the people who don't agree with the current approach have mostly left, polling active users no longer accurately samples the broader community that the space was meant to draw on, but rather the people who happen to agree with the current approach.
3. An employer begins to remove people who don't agree with his strategy and hire those who do. Now, everyone in the organization is on the same page with respect to the strategy -- but when that strategy has flaws there are few internal voices that are able to point that out.
4. A person who recently moved is having some social difficulties fitting in to a new community she's joined and asks her old friends for advice; because they are already her friends and enjoy her current manner, their advice is not very useful for helping her adapt to a new context!
5. A company developing new technology overfixates on their current market and falls prey to Galápagos syndrome; their products become overspecialized with features for their existing group and are no longer competitive in the broader market.

Focusing too much on those who are currently present can be insidious because it can be self-reinforcing; once one is focused on an inappropriately small group of users, confidants, or advisers, it can grow increasingly difficult to bring in information from outside this perspective. Further, one who relies too heavily on a certain perspective can ultimately alter their plans in a direction that further reinforces that small group's desires, driving more of those who don't agree out, and so on.

In order to avoid this cycle, it's important to "look to the river but think of the sea"; in other words, consider not just those that are currently in front of you but also the broader group you hope to reach in the longer term. Solicit outside perspectives or alternate takes and seriously engage with them when making your own plans. In some cases, doing this can be hard -- but that doesn't mean it isn't important.

One example of how I put this principle into practice in my own life was with an online event that I run in another community I'm part of. At one point I decided to run a feedback survey as to how to best to run the event, including people's thoughts on how best to make certain controversial decisions. I made sure to circulate that survey both to those who had participated in the latest season of the event and also to those who hadn't!

By surveying not just people for whom the event was already working but also those who weren't participating, I was able to make changes that helped reflect the will not just of the people who were already enjoying the event, but also that of others in the community the event drew from. After having run this survey and made resulting changes, the following season of the event was its most popular ever, with almost twice as many participants.

Now, I'm not saying that making these changes was crucial for bringing all those people in, as there are other factors to consider (increased publicity etc.) -- but I was very satisfied with the result, and I think if I had just polled those already part of the event the result would have been significantly worse.

After all, if you want to make a difference for more than just those you're currently interacting with, it's important to make sure you don't forget yourself in the current milieu!