How do I change careers when I have specialized too far?

You went deep in one narrow field, and now the depth feels like a cage. The more senior you got, the more it would cost to walk away, so the very success that should free you seems to hold you in place. That is a real trap, and it is worth naming plainly. But look again at what you actually built. Under the specialty are broader things: judgment, the ability to learn something hard, credibility, a way of thinking. Those are not stuck to one field. You feel you would lose everything by changing, but most of what you value would travel with you. What you would lose is mainly the title and the certainty, not the substance. You do not have to leap. Explore from where you stand. Spend a little time near a field that draws you, talk to people in it, take on one small project that stretches you sideways. Test the water before you decide the door is locked. Often it is not locked. It is just heavy, and you have not tried the handle in a while.