I've had a lot of existential issues with this. What makes me feel better is that the system in the moment is what matters. Everything gets destroyed in the end as per every world view (goes to a heat death, gets destroyed by Yahweh and a new Earth comes about, wolf eats everything). Nothing you build will last more than one or two generations, statistically. Just enjoy making the thing and the process of trying to solve a problem. Maybe pick which problems you work on.