I would echo the common sentiment here that personal projects could help you in your development, and break away from monotony. At the very least, learning something along the way and demonstrating it can increase your marketability if that's something that concerns you. This is my current strategy. I'm not exactly anxious about my future, but I think it's reasonable to hedge bets with lifelong learning.

Another primary driver for my starting side-projects, which I swore I wouldn't do because "I already program enough at work" (I think this is fair when I'm burned out from it but I feel that less and less often as I improve), is that I want to be more creative and less consumptive in my free time, with something I would value.