Lovely, lovely essay by Tim Worstall, which starts out with the usual speculation about Facebook valuations and winds up in a really interesting place, summarised thus:

And that’s the little secret about infrastructure that is so little understood. It is not true that having infrastructure makes us or the society richer. It is rather that using it does. And we usually don’t know how to use it until someone has gone and built a lot of it, people do that curious shaved monkey thing of experimenting with it and then we all find out. This is true of most inventions: it has been said that the biggest social change that the Model T brought was that women were less likely to be virgins at marriage. People worked out what to use the back seats for pretty quickly. The bicycle has been called the greatest contribution to the health of the working classes ever: it allowed courting outside the home village for the first time (amazing how inventions and sex seem to go together, eh? The first social network, Friends Reunited, is said to have caused a bubble in the divorce rate) to the benefit of the next generations’ genes.

So these bubbles, they’re not all bad. They provide an excess of whatever it is, which we then play with until we’ve worked out what to do with it. What we do with it is what allows the advance in wealth, even if those who built it for us have gone bust.