When you're skiing at a high level you have to either be very rich already or at some point start getting well paid, which is rarely what happens when your thing is doing unique tricks and having a specific style and your popularity exists within a small part of a niche community.
So when you get to a certain age and want to move on with your life, lasting relationships, etc. , it's necessary to find a way to make a good living and find different ways to engage with skiing.
Once you hit your early 30s, the pain can really start to hit too.
Cole Drexler said something to the effect that it wasn't worth it to keep skiing professionally for free equipment and a small travel budget when he quit.