“it isn’t religion, it isn’t belief, it’s money”.

I must respectfully disagree.
It IS religion “what really fuels the Jihad”, though perhaps not religion as we know it, Jim.
For real die-hard idealogues, it is always The Idea that matters. It may be a religion, or political or tribal system, but whatever form it takes The Idea is The End, and The End justifies The Means.
Different terror groups may seem to have different messages, but this upper-echelon psychopathic mindset is the same, whether it be Hamas, the IRA, Sendero Luminoso or the Taliban.
Like psychopaths, these idealogues lack empathy, seeing other people as mere objects to be used to achieve The End. Therefore, The Means are whatever it takes: robbery, drug-dealing, sex-slavery, appalling torture, random killings, no crime is too terrible, nothing is ruled out.
For the Jihadis, the Idea is Jihad, and imho it makes no difference
whether a particular action is “explicitly condemned by the Koran”
or not, so long as it works to the advantage of The End. Broadly, their argument is that the Koran only limits actions between true Muslims, and that everything is halal in Jihad against the kuffar (a grouping which includes noncompliant Muslims).
When very large numbers of Muslims are active in Jihad, it is almost inevitable that many of them will be a bit shaky in their faith, being seduced by the money, the drugs, the thrill of violence, or just the general excitement of life on the edge. However, being Muslims they will still feel a need to reference their actions, to seek approval within some kind of Muslim framework, and this “moral” support is provided by the idealogues of AQ and the Taliban.
I DO agree that attacking the Jihadis various criminal activities is vital, because that reduces their income and inhibits their networks, and may help to uncover actual terror cells and foil attacks.
The But is, and it is a Big But, that even if we could follow the
money all the way the end of the trail, there we would still find
religion, and a bunch of idealogues mumbling “Allah permits, Allah permits…”.