Isn't this what Ycombinator is all about? If you want fulfillment, start your own company and create the job that you are passionate about.
I only escaped burnout via an 'ah-HAH!' moment when reading up on strategy creation, and realised that I needed to start cutting down my workload to only what really matters and nothing more.
A startup environment is a terrible environment for anyone who cant cut through the weeds of the nice-to-have to see only the necessary.