I think the more common reaction is the other way around. The book was revelatory when I read it (as a young teen), but when I returned to it years later, after studying philosophy, I was surprised by how shallow it really was.
I think that books like this are life-changing if and only if they connect with you at the right time. Put another way, the number of life-changing books one reads tapers off quite quickly after, say, 30.
I think that this book, like Atlas Shrugged, is one of those that can lead to a mental confirmation that what a teenager thinks is the whole truth and everyone else who doesn't understand is just plain wrong. Doesn't happen with every reader, but a higher than normal proportion read it and then turn into single topic lecturers for a while. Hopefully they grow out of it. (I hope I did).
I think that books like this are life-changing if and only if they connect with you at the right time. Put another way, the number of life-changing books one reads tapers off quite quickly after, say, 30.