Shmukh user al-Sakit argues that you need a wide distribution of jihadi propaganda on mainstream forums in order to attract a small amount of people. He observes that the three top mainstream Arabic forums have one million users each. If you post jihadi propaganda to all of them, only 10% (300,000) are likely to look at it. Of those, 10% (30,000) will like what they see. Of those, 10% (3000) will embrace the idea of jihad. Of those, 10% (300) will propagandize. Of those, 10% (30) will go out to fight in a jihad. Of those, 10% (3) will seek martyrdom.
That’s much the way I think about it, which is why countering the effects of jihadi propaganda is so difficult. It just needs to mobilize a few.