In this respect, techies are like anybody else. Some are out to help save the world, or at least make it a better place, and some aren't. It's not the tech that makes the savior, it's the person.
The same can be said about:
- finance folks (microcredit vs subprime mortgages)
- engineers (postwar reconstruction vs weapons)
- architects (affordable housing designs vs Trump towers)
- builders (habitat for humanity vs suburban subdivisions)
to name a few examples.