Especially with Japanese Mangas, I can understand the appeal of piracy. Most of them officially never see the world outside Japan, so they are very hard to obtain for international readers. Which are a big part of the fandom, though.
So (apart from the stupidity of the tale that every copy would have brought 100% of the sales price if there was no piracy) the losses are primarily due to simply not selling their products on markets that are showing demand.