Since fiat is mostly just used to enable war, and most all war, especially in modern history, is senseless slaughter: we should do everything we can to subvert fiat.
First - I think you are wrong about "war" part. I'm reasonably sure that global military industrial complex mostly uses digital money transfers. I think what you were talking about was a small scale rebel or terrorist armed operations, but those are rounding errors in the scale of proper war industry.
Second - you are quite right that cash is used for that and without it such activities will greatly diminish. Though I suspect that they will switch to barter economy.
Third - that will happen soon. Some governments are already restricting cash, though mostly the ones that are doing so are fighting not against wars or cartels, but against their local oligarchs funneling money from the country (the same problem I described in other comments). Many countries have already restricted moving cash across the border, so there it's not used for this a lot.
> I'm reasonably sure that global military industrial complex mostly uses digital money transfers.
It seems like your concept of fiat might be wrong. Fiat isn't synonymous with physical tender. Fiat is just sovereign money in whatever form it takes, digital or otherwise.
Governments enforce fiat as money because it allows them to finance whatever war and other endeavor they want with an endless supply of money that they conjure out of thin air. Whereas taxes are at least paid by people, fiat is a way to steal money from ordinary people by debasing their money.
Second - you are quite right that cash is used for that and without it such activities will greatly diminish. Though I suspect that they will switch to barter economy.
Third - that will happen soon. Some governments are already restricting cash, though mostly the ones that are doing so are fighting not against wars or cartels, but against their local oligarchs funneling money from the country (the same problem I described in other comments). Many countries have already restricted moving cash across the border, so there it's not used for this a lot.