How do decentralized apps like Casa or OpenBazaar make money?

I couldn’t find any information about their business model. Does anyone know more about this?

What I understood so far, business model on blockstack is simple and interesting. Application creators are rewarded on the basis of active users i.e. bigger the user base bigger the reward will be. And if application also has a namespace then creators are paid whenever any user registers to that namespace, this works exactly like domains, buy domain and renew domain in exchange of money.