I think there are many others one could point to more accurately, including Yahoo who purchased and then resold tumblr.
While Tumblr has made a lot of changes, some of which were walked back, they are still a well used and beloved site today. There are many now-dead or barely alive behemoth Internet companies that are better examples of "poster child for running a terrible Internet business" imo.
Maybe try a new non work hobby in this downtime. You don't have to be a more productive or engaged employee to find joy and excitement in life! Why can't work be that consistent but dull backdrop that empowers/enables your the rest of your time?
Maybe a mindset shift will help. You don't have to keep climbing that corporate ladder. Stop and smell the roses! Idk about you, but most above me on that ladder at my company seem pretty overworked and tired