A community does not need to be making its creators money hand over fist, or indeed making money at all to be successful in terms of what the users expect/want from it.
In the same way, most /b/tards would leave if 4chan became anything resembling a legitimate business. There are far too many alternatives out there, and while moot is generally well-liked, not too many people feel a great sense of loyalty towards him. /b/tards have left in droves over far milder insults than trying to make money off them.
The other problem is the content on /b/. It's nearly impossible for moot to find advertising partners, given that gore, beastiality, and child porn are posted fairly regularly. Not many legitimate companies are will to risk being associated with that, so /b/ has had the same banner ads for months on end. I can't imagine they pay much.
do you have any evidence supporting this claim?
The captchas have mitigated the cp, but I still run into it whenever I visit the board, an activity in decline.