You might have a look here:
FAQ: How do you pay the bills?
It’s actually 88,50 EUR per month… and now compare to server costs and also discourse service… not speaking of the time of “the staff”… (and they aren’t employed…)
(BA also just updated the space to another 1GB).
So yes they make some money by adding “the default advertising” which is done by some big advertising company and based on your browser history…
And you propery/mostly have an account for your mobile at the same company… so now they even know where you are and using what app and making money with your data. Or even for their other services (auto login etc).
Think about that… 