Online Marketing Conferences: Who Attends?

Sometimes as an exhibitor at a search or online marketing related conference, you get pre-show attendee lists. I looked at one for a recent conference and thought the numbers were interesting:

Investment bankers: 1%
VC's: 2%
Advertisers: 18%
Agencies: 20%
Publishers: 20.5%
Service Providers: 24.5%
Ad networks: 0.5%

I don't know what to make of this except to say there are too many agencies and publishers chasing too few advertisers, and why oh why are there more investment bankers than ad networks?