The operational costs are considerably lower with Blockstack, since the app doesn't host any user state (and in many cases, no state at all). Most apps don't need a database of any kind -- all the business logic runs client-side in the user's web browser.

Event if operational costs going to be 0, it's not a viable business model to not have profit.

I never claimed otherwise ;)

However, I will claim that the lower operational expenditure (and lower liability for holding user data) makes profitability on-the-whole easier to achieve in Blockstack-powered apps.