Right, it's easier to cut their supply of resources and they will bleed out, but as long the US, Russia and every other nation out there won't stop resupplying them for blood money, nothing will change. It's plain business.
You also have to stop people from joining terrorist groups in the first place. Many of the people that joined the insurgency in the Iraq War, for example, were members of the Baathist party that the US put out fo the job when they liquidated it. The more desperate people are, the more they're willing to do to make a living.