The article here asks, in effect, why economist bloggers blog when they don't get paid for it:
Like millions of others, economists from circles of academia and public policy spend hours each day writing for nothing. The concept seems at odds with the notion of economists as intellectual instruments trained in the maximisation of utility or profit.The question can be generalized to most of the rest of us. Why does anyone? Some of the answers provided by this piece: a place in the intellectual influence game; the sharpening of ideas; an extension of educational activity; having a voice. Of course, one can also question the question. People do a lot of stuff they don't get paid for.