Why do people Join Groups, but never participate.

I have been a member of IN since Protected content to this day I do not understand why people become a member of a specific group, but never take part in the activities of that group.
The only logical explanation that I am able to formulate, and please do give me your input, is people just want to show off when they have a conversation.
In this Facebook wannabe age of showing off, it is obvious that people, in general, and I want to stress in general, have a need to show that they are more than what they really are, just like any social media website IN is no exception.
People join groups just to have their name in there, not because they are really passionate about a category, but just to have their name on a list.
I have hosted and Consulted many different groups over the years and I have noticed groups with over Protected content yet if we look closely to the groups we can notice that in reality most of them are just a list of the same old names that appear and never participate in the activities.
IN is a business just like all the other social media platforms that offer opportunities to take part in some really nice activities, but this can only happen when the names on a list actually participate in the activities offered.
My conclusion is supporting groups is great, but take part in the activities if you are a member, just don't be another name to show off.
If you change countries/cities take the time to remove your name and update your status from a list it only takes 1 minute and it helps the Consul of the group.
The most frustrating thing for a Consul is the No Show rate of an activity, don't click on an activity and join if you know that you will not take part.
We are all social people and we all like to have options on a certain evening of the week so we keep ourselves open by joining many events at the same time and date, this is a destructive practice for a certain group that many times counts on our presence to be successful.
IN HQ is incapable of resolving this issue so I appeal to the members to help in at least reducing this problem by becoming more responsible and considerate and only join groups and activities if you really intend to participate.