No everyone needs a 3d printer for sure. A big part of what stopped the idea that 3d printing would be this magical revolution is that designing plastic parts is actually fairly hard.

I don't use my 3d printer to 'fix' things around the house that often because it's frequently cheaper to work around it or buy a replacement. The times a high-value item breaks in a way I can fix with a printed part are rare enough it certainly doesn't justify owning one.

That said, if you really like designing mechanical things or working on electronics projects or similar, a 3d printer is a total blast. I'm currently using mine to make molds for real ceramic parts.