I would not say that they jump in “when needed,” at least not anymore. In the past, the volunteers would get at least a little bit of chance to sub things themselves. Nowadays most shows that don’t already have presubs from the content provider get subbed (and thus also segmented) by the staff before they even air.
Of course, we do have a lack of volunteer subbers here, but this way even the few we have left will leave. And apart from for the subbers, it also makes a big difference for the segmenters, who for most shows now end up checking ready-made segments instead of creating them from scratch. And that does not speed up the process since it’s actually more work.
I don’t think there is one answer that’s true for every single abuser. For some it might be the free Viki Pass, for others the sense of belonging, “accomplishing” something, the kick, a feeling of control, who knows? Maybe it’s even an addiction…
Probably. The more they sharpen the rules, the harder things get for the innocent people, as well.