IMO study whatever you like, no? For me being deeply immersed in a topic that doesn't 1:1 translate to an improvement on the CV is its own pleasure. This way I get to read (complex stuff) for pleasure because it isn't connected to the career hamster-wheel. There is no pressure, while at the same time directly improving my foundation - whether that is Philosophy, pure Math or niche-History does it matter?
> better off focusing on what's actually in the modern world.
this might change your mind: https://www.suhrkamp.de/rights/book/andreas-reckwitz-loss-fr... (If you only want to study what's actually happening in the modern world, this is the one that explains the loss from Modernity through a sociological lense)
I recall N.N. Taleb also making some good points about why to read books that have stood the test of time rather than a best-seller.