Eric Limer writes:

When Reddit was first started, it was populated almost entirely with content submitted by fake users.

In a video for online educator Udacity, Reddit cofounder Steve Huffman explains both the method, and the reasoning behind it. Essentially, Huffman set up a submission interface through which they could pick not only the URL and the title, but also the user’s name. Upon submission, the name would be registered, and make it look like Reddit had more users than it actually did.

The plan was a very “fake it ’til you make it” sort of thing; by submitting the kind of content they wanted to see under the guise of being other people, Reddit’s founders were able to attract exactly the kind of people they were pretending to be. The overall effect was that, over time, all of these fake users basically were replaced by real people who, for all intents and purposes, said, did, liked, and submitted the same things the fake ones (Huffman and fellow cofounder Alexis Ohanian) did. It jump-started the site.

It's no wonder Reddit is populated by mean, fake people.

They are the descendants of an original sin of populating the place with fake people.

This is a growth hack I do not recommend. Dishonesty is not a strategy.

Sangeet Paul Choudary adds:

Reddit co-founder Steve Huffman admitted that the link-sharing site was initially seeded with fake profiles posting links to simulate activity. The key was that the links being posted were the kind of content the founders wanted to see on the site over time. Reddit not only gathered steam, the initial content also attracted people who were interested in similar content and created a culture of good content in the community.