Reading his stuff at 10-15 years old can set you up with a follow-up reading list that lasts decades and reaches way outside of scifi. As a human being, there's some very real benefit to explicitly grappling with ideas like Cartesian solipsism at ~12 instead of hearing about it for the first time at ~20 in philosophy 101, but there's also some real dangers too! Besides being well read, PKD was obviously compelled to imagine the logical conclusion of almost everything he encountered in his life, including socio-political trends. While this inclination obviously bestowed an amazing gift, if you look at biographical elements of his life, it's equally obvious that it was a curse. There's definitely such a thing as being way too smart for your own good.
His prescience on many topics is well known, so I'll skip that and add something more obscure. I'm very pleased that PKD is gradually becoming recognized as way more than just some pulp / SF writer, or just another prolific pop-fiction dude (like say Dan Brown or Stephen King) with an existing audience that Hollywood can monetize. PKD deserves much credit in the high-brow postmodern canon too, and although it's not widely realized yet, probably has done more to pioneer and popularize truly experimental fiction generally, and metafiction in particular, than almost anyone else you could name.
Since I recently reread 3-stigmata, I will also quickly remind everyone that Choosy folks choose Chew-Z. As of today, it's uncanny how much Palmer Eldritch looks like an unholy combination of Zuck+Musk.