What I notice is that professional/business services tend to last longer (i.e. Skype, linkedIn) and are more stable.
Steve already posted a blog entry regarding that some time ago.

But when it comes to pure (non-productive?) sites attracting young people, it is as volatile as a dangling C pointer

Honestly, the idea that Facebook is somehow different to other internet fads is a total myth. Most of the people that think this grew up with Facebook, so since they’re of it’s generation they think that it will last forever – the typical hubris of youth History simply does not agree – ideas and fashions expire, the next generation (of internet users, rather than people – cycle every 5-10 years) will use something else. When Facebook eventually sells up to a bigger player, it’ll start in earnest – it’s what always happens.

@Paul: I just detest the hype train around things like this. I hated it around time of the dot-com bubble too, I dispaired at the amounts of money that were flying around with little real sense attached. After 2001, I just can’t believe people still fall for this anymore.

Perhaps by then everyone will have mobile phones running open source software and servers, hosting their own content using a unified standard that allows the kind of social networking those properitary sites that hoard all your data currently do.

… or not.

And although ad revenue looks high now, it’s probably not proportionately; because although there are more people browsing these sites, the sites themselves cost more to run (massively more storage and bandwidth required than the 90s), and the competition is far more intense. How many years of strong profits would it take to pay back the price of Facebook if someone bought it now? (even if it went for less than the crazy $15bn) – they’re turning over $200m or something right now and making zero profit. Of course Mark Zuckerberg thinks that growth is more important than profit, but will his company really last long enough to make that ‘strategy’ pay off? GeoCities suggests not.

I previously thought they would be able to hype it for long enough that some poor sucker like Yahoo! will buy it at its crazy inflated price before it nosedives, but with the economy the way it is now I’m not sure so many people will be willing to indulge companies like this, that look great on paper (2 zillion users!!) but which just burn money rather than make it. But, they’re still “hot” so as long as they can keep bullshitting on the profit line they probably will find a buyer and Zuckerberg can retire.

Perhaps it’s not really true though, as Google’s 2008 AdWords turnover was 21.8 billion of which 4.2 billion profit. I don’t know if the whole Internet made that much money with advertising back in the 90s.