What do I do when I fear the power of what I build?

You build systems that reshape whole products, and lately the scale of that has started to frighten you. That fear is not paranoia. It is conscience. You are close enough to the work to see that what you make affects real people in ways they never see and never agreed to. Most builders never feel this. That you do is a good sign about you, not a bad one. Fear like this is asking you a question: will you use this power carefully or pretend it is not yours. You cannot un-build what you know how to build, and stepping away would just hand it to someone who feels nothing. The honest path is to stay close and stay responsible. Power in the hands of someone who is afraid of it, in the right way, is safer than power in careless hands. So turn the fear into practice. For the next thing you build, ask plainly who it could harm and how, and design against that harm as seriously as you design for the feature. Raise it out loud with your team, even once. You do not have to carry the whole weight of the field. You just have to be one person who refuses to build as if the power were not real. Start there.