I buy both physical copies and pdfs of the things I am actively playing, usually -- one goes on the tablet for me, the other goes on the table for my gaming group.
I only buy things I plan on running/playing tabletop-wise (online or off, I do both) and do not purchase books in any fashion for general mushing any longer (and probably won't ever again). If I am not interested enough in an RPG to run it or play it in a tabletop form, I'm not gonna be interested in playing it on a mush anyway.
Mind, I end up buying LOTS of books. -.- If something is interesting and recommended to me, particularly new tabletop games with something cool to bring to the table, I'll buy it with the intention of seeing if my tabletop group likes it. In this case, I'll buy the hardcopy generally. If it ends up being A Thing We Play more than a time or three, then I'll grab the pdf too.
I pretty much don't/won't play games that require eleventy billion sourcebooks any more, in any aspect of things. If I did decide to go back and play WoD (of a form that I don't already own the books for), I don't think I'd buy more than the core book, even with all the splats available. I also wouldn't pirate them.
SOMETIMES I will borrow a pdf from someone who does own it, but I cannot think of a time in the last couple of years when a PDF was shared with me that I did not then go out and buy the book within a month or so (if it was something I ended up using).