Large-scale pirates that can actually reach a significant amount of people almost never rip-off indie creators, and even if they do, they are the least likely to impact sales - people are unlikely bother acquiring illegitimate copies of obscure indie works as against big-brand stuff whose names they have actually heard of.

I really doubt the sales of the graphic novel that friend of yours were impacted in any non-negligible way by it being ended up on a piracy site. If anything, it might as well have worked as an advertisement.