You need to work on projects that you genuinely feel passionate about, not just random companies to pay the bills. You can still be a part of a bigger system but feel great about the work / product that your company is putting out.

If you feel passionate about social networking, work on facebook or twitter. Hell, twitter's existence was almost solely responsible for enabling the Arab Spring uprisings in 2011 and 2012, resulting in some pretty widespread social changes.

If you feel passionate about Open Source, try working for RedHat. If you think AI is going to be the next big advancement towards human progress, try to get on at IBM or another research time devoted to it.

Are you really saying that there aren't any problems out there that you feel a need to solve, that there aren't any companies solving them that you'd like to work for?