I think this is the biggest tragedy of refusing to let go of sunk cost:
You sacrifice other opportunities because you are stuck living with that decision.
Something bigger and better might be waiting for you, but you can’t accept that you might need to give up a career that took you decades to build.
Ask yourself if you would make that same decision knowing what you do right now and what you will experience moving forward from this point? Set aside and ignore the sunk costs for now.
Ask yourself what you would recommend to someone else in this same situation? Would you really tell them to keep sticking it out, even if they were miserable and unhappy?