My take on it is that there are very few career paths to follow where wide-reaching, positive social change is the whole job. Doctors, social workers and politicians all have to compromise and do work they’d rather not do for a lot of the time.
I guess that as industrial designers we’re sold the idea that we have the chance to change the world because products can reach so many people, and that is an exciting opportunity, but doesn’t mean it’s always possible.
As many people have already said, do what you do as well as you can. The small details you put into a product may not save anyone’s life, but if 100,000+ are made, it could change a lot of people’s lives a little bit.