We see ads all the time on facebook.

But there are reasons, why I am here and not on facebook. :)

As I suggested in another comment, what about giving (only) these users who allow advertisements a small reward (could be a low percentage from the money the advertisers pay Steemit Inc.)? In addition it would be a very interesting model to let the users decide themselves which advertisements they like to see on their blog (and get paid for it) and which not.