Odds are that I could make more with one than most people here could.
At the very least, it requires a bit of skill with CAD software to even make a model of the finished product, plus a bit of computer skill to turn that CAD model into code that the printer will accept. While there is free, open-source software to do both of those, the software isn’t exactly user-friendly enough to read your mind and make a flawless CAD model and program; you’ll need at least some computer skills. Maybe in the future that will no longer be true, but that will be after we have volitional AI. See here for a bit more info.
There is also the engineering end of it. You cannot always print the finished product directly. That is especially true if there are “undercuts”. You will have to be mindful of the geometry of the desired part(s).
As for what one can make with a 3D printer, how about a car? Yes, despite all the hoopla frop the MPAA about piracy, even Porsche wants people to download a car. And I know that 3D-printed parts are used to make molds used in foundries to make certain castings as well. Or maybe prosthetic hands. Many things are possible!