Cant speak for everyone, but in my case, Ive done the grind to get something cool done in my younger days. Ive designed, programmed and tested a differential braking system for a sizeable unmanned aircraft technology demonstrator, from hardware to drive the master cylinders, to the software with control of stepper motors following dynamic control laws, and then sat in a control room at a US Air Force base and watched the traces as the real thing was landing and purely steering with the brakes after touchdown (to test nose wheel actuator failure).

At my current company, when I got hired, I specifically said upfront that my goal is just to become a subject matter expert, and to have a more consistent and chill workload. I did what I was supposed to, nothing more, but I did it correctly, and put in extra hours when crunchtime before deadline came. I got promoted to senior after 4 years, and now Im pretty at very minimal hours of actual work per week.

But, because Ive been on the same team for so long, can answer questions about the entire tech stack, I can debug things, I am happy to sit in meeting and talk about high level things when managers don't want to, so my value is still fairly high. I no longer care to really put in hours to build something cool, instead I am focusing on things I didn't have time to do when I was younger and grinding, like travel and fitness.