Why would someone join an empty social network?

There are actually some very compelling reasons for joining a new network while it is still very empty:

Brand protection. By creating an account while a site is unknown you can get your first choice of username and vanity URL. Wait too long and someone else might grab these. It costs very little in effort to join every new networking site just in case one becomes important later. And if it fails you didn’t really lose anything.

Desert island effect. While there are still very few users in a network everyone talks to everyone so you have an opportunity to talk to people who might normally not be accessible. I remember the first days of Google Plus when there were no cat pictures and so many interesting people. Quite often the people you meet in the first days are founders, employees, investors, early adopters and other cool people.

Bragging rights. When the new site becomes massively successful you can tell people you had an account before it was cool and that your user ID is 3. If you never say that you join every site people will just assume you are awesome at trendspotting.

War stories. When the site is popular people will start asking on Quora what it was like in the early days and you will have the answer. I use knowledge like this routinely in articles, in lectures and in the business school courses I teach. Having an actual memory of what things were like saves a lot of time in research.

Of these brand protection and the desert island effect are the most important. Brand protection ensures that your personal brand is not diluted by other people and the desert island effect lets you talk to some very interesting people.