Not every company has to claim to solve problems that change the world.
Silicon Valley Has A “Problem” Problem
Riva-Melissa Tez

I run one of the few startups actually working on this type of problem. mWater makes project management and collaboration software for water and sanitation in low-resource regions of the world. We help people safely and sustainably create and monitor water points and other critical sites in 59 countries. Interestingly, for the point of your post, despite constant and repeated effort, we have never been able to get support from Silicon Valley. My sense is real world changing problems are too horizontal in nature. They involve infrastructure and complexity. Most of SV has made its success from vertical approaches to issues with little complexity. The few SV approaches to humanitarian causes are failing badly for repeating that simplicity.