From what I heard, most people feel regret at their deathbed for working too much, not the other way around. While you seem to have noble motives, I think many jobs out there don't provide much value and don't advance society as a whole. Think about large parts of the entire financial industry. Yes, the financial industry is important for a stable economy and a high standard of living, but there's a substantial amount of jobs that don't do much but redistribute wealth between individuals. It's really silly.

The biggest question is: What do you want from life? And one way to find out is if you answer the question:"Would you be doing the same if money wasn't an issue?". I think contributing to society through work is hard to define and overrated. Do you think all these silly apps make a difference on the grand scheme of things? Probably not. Does society really need smartphones? It all depends on you and your own values. If you do things that bring you joy, you might be doing more for a healthy society than if you create value through some job that you wouldn't do if money wasn't an issue.

Edit: I started to read this blog recently, which tries to answer what makes a life a good life. Maybe, you'll find some inspiration in there: http://earlyretirementextreme.com/