You are absolutely correct and let me elaborate a bit more. If you have a two sided market, you should build personas for each side — that line up with each other. By lining up, I mean the side with the supply creates the supply that the demand side is looking for.  It is possible then to make money off both sides or just one side (i.e., one or both sides would not just be the end user but also be economic buyers meaning they would pay you for using your platform). It is also the case that you could allow both sides to use the platform and if you are able to capture the data from the end users (via Terms of Service agreement and general market acceptance of being able to reuse the data), you can also be successful IF that data is valuable to a third economic buyer. That would be yet another persona.Then is would be a three sided market. By the way, it only takes one economic buyer willing to pay enough to make the model work but don’t discount the possibility that you can get multiple sides to pay for your service (like LinkedIn does so well) and it will make your economics even more attractive.

Petra, by the way, sorry it took me so long to respond. Usually I respond to forum questions every Sunday but it was a big holiday last weekend.