I am trying to be argumentative, but I am just curious if you do not buy traffic, then where have you heard that this type of traffic has no chance of getting converted into leads?
There are numerous business models (automotive, dating sites, etc.) that have been extremely successful buying traffic and converting it into leads.
Buying traffic works much better if you offer a product or service, because you know how much your product is worth and after testing paid traffic for awhile you can easily determine your conversion rate so you know your margins and at what price you can purchase traffic to be profitable.
Knowing this data, actually makes it a much simpler business model to control and execute.