What about you? Do you only buy materials you intend to use at your table? Do you buy materials just to read or just to push the hobby in directions you appreciate?
I buy some for reading alone - usually in bundles so I get much of a line in PDF for the cost of the corebook.
The ones I buy dead tree are usually bought for use.
Many PDFs I buy on speculation of being able to run them.
Warlock, I picked up to see what someone else was on about... I then started grabbing the other books for it because, despite low probability of hitting the table, it's an interesting read. I like extracting setting from tables & Mechanics.
Blade Runner... both my groups want to try. I want the game. So, dining budget chopped for the month...
Talisman Adventures... bought the PDF, loved it, bought dead tree, ran it... advancement is a bit fast, but it's a fun low-prep. Plan to get the Dungeons supplement when it ships next month. It's a seriously quirky setting. I plan on it next,,, for one group or the other. It's also almost all player facing rolls... (exceptions: encounters, NPC damage to PCs)
I bought the Numenera bundle because I wanted to know why it's so hyped... and so despised... It clearly points to Monte Cook upping the Dying Earth influences quite a bit from his d20 system roots; the system has a very different approach to attributes; I find that interesting... but I don't have much interest in running it. If one of my groups asked nicely, I'd run it. I doubt they will.
Only three dead tree purchases in the last year are likely to not see play...
Neoclassical Greek Revival - was curious, was on sale, and the PDF+POD+Shipping was a few cents above the PDF usual price.
ACE core... price was right. Again, PDF+POD. A sale (possibly with errors) put it pennies more for PDF+POD. Too light, too constrained, but man, it reads well dead tree. I'm not averse to running it, but have no
TOR2e. thanks to the PDF, I know the offset printed one won't see play, nor will the PDF. I'll stick with 1E as a far better game and much further better Tolkien feel.