Friedrich Blowhard has been reading American Demographics magazine, which apparently tells him that
Financially, visitors to blogspot.com are either rich or poor; those making under $25,000 or over $100,000 a year are over-represented, while middle-income visitors are under-represented.
My theory is that this means that bloggers consist of two groups of people: smart people who are presently employed (and are paid a lot for being smart) and smart people who are presently unemployed (because lots of smart people have lost their jobs in the last couple of years). More normal people don't use the blogosphere yet. The key question is whether they will.
I am by no means the first person to connect the collapse of the tech boom with the rise of the blogosphere, but certainly quite a few blogs have been started by people who suddenly found themselves not working, but who suddenly found themselves not working. They, or in fact we, are the sorts of people who feel the need to do something compulsively, and blogging fits the bill perfectly.
The other less new explanation is that there is a student/non-student split. Certainly this was true of internet users in general in about 1991. There were people who were still studying or doing post-docs or something, who didn't have much money, but who were likely to make a fair bit when they actually got jobs, and there were people who had actually done this. This effect is not as big as it once was, but I think it is still there.