I once wanted to work at a Lithium Ion battery start-up because I wanted to help create an energy source free of geo-political and climate turmoil. Then I discovered those sources were some of the most toxic to the environment both in the harvesting and the disposing of the material.

I then went on to do graduate research in explosives detection. We created machines that would help detect bombs in Iraq and landmines left in a peaceful villages. But then TSA used the machines to look at people's private parts and there was a mass privacy scare.

My point is: you can't go life worrying who might use the things you create for harmful purposes. You may be ignorant, but the alternative will drive you insane.