In Muslim countries, the problem with funding of terrorists groups isn't well addressed. It seems that enough wealthy people feel that their money is well-spent on armed thugs, as long as they have the right religious persuasion. I imagine that donors hold these views when they aren't personally subject to the thuggish behavior. So I'm left hoping that they either wise up or get a taste of their own medicine (preferably the former).
The financing of ISIS reminds me that some Somali pirates were also well-financed, but with the clear aim of turning a profit. Who would have known that the pirates would be replaced with an even bloodier threat. I hate to think about what's next.
Extra. Another article focuses on ground-level operations--extracting protection money and controlling financial hubs.