The network effect of reddit are also much less than twitter or facebook, it's primarily a news aggregator + comment system, there are plenty of competitors ready to step in if reddit starts throwing in tracking or invasive advertising.
> I've also heard that it only makes $10 million a year in revenue.
What's wrong with that? Not everyone wants to be the next google or facebook, I'd love to have a site that made $10 million a year, I'd be perfectly content with that and wouldn't have a desire to turn it into a multi billion dollar empire. ~20 years ago this was the dream of most software developers, carving out there own ISV niche and getting rich.
Unlike twitter, reddit is a sustainable business. If I had to bet on which one will still be here in 5-10 years I'd bet on reddit.