During the war with IS there were constantly talk about how funding terrorism goes directly into funding the wars, be that people who directly gave them money or people who bought their drugs. I also often see the police say things like "don't buy things from criminals, it directly fund more criminal activities". We have international agreements against blood diamonds and conflict resource, all focusing on eliminating the finance of those conducing wars. It seems that in every possible way where people are funding war and conflict, the message has been in the past 20-50 years that this is actually a problem that need to addressed. While cutting the funding doesn't imminently stop conflicts, or prevent terrorists from making home made bombs, giving them money does prolong conflicts and gives the warring faction more options to continue doing horrible acts of violence. Cutting the money flow also provide pressure on the targeted population to stop their leaders and forcing them to the peace table.