From Adrian Goldsworthy's How Rome Fell: "Civil war remained a common event, ...the economy collapsed, as successive emperors massively devalued the coinage to pay for their wars."
Other sources say the emperors debased the coinage to pay soldiers for wars for the empire (i.e., not for their own civil wars): "This income was not enough, however, to cover the entire cost of the new army [made in response to the new Persian threat], and in the late third century emperors also pursued two further strategies. First, they debased the coinage..." (The Fall of the Roman Empire by Peter Heather)
So did the emperors debase the coinage for their own civil wars, or for wars against external enemies?
"By 268 there was only 0.5 percent silver in the denarius." (mises.org/daily/3663 - transcript of Professor Joseph Peden's lecture)
Did such huge debasement occur as a result of the emperors' need to fund troops for their civil wars, or for foreign wars? It seems that it was likely a combination of both, but which played a bigger part in causing the coinage to eventually be reduced to less than 1% silver content?
If it is hard to say, are there any examples (hopefully more than a few, and at least fairly significant) of certain emperors debasing the coinage mainly due to their civil war?