Although it is getting better a lot of articles about 3D printers and 3D printing concentrate on the tchotchke factory aspect or the high end metal printers and ignore the simple, utilitarian uses that are a much better example of the impact of this technology.
The charging cradle for my Samsung Gear Live smart watch broke a little while ago (there is a small clip that holds it to the back of the watch, if that snaps off it becomes useless). Samsung no longer manufacture the device and replacement charging cables can be difficult to get. Because I have a 3D printer available it was easy to quickly design and print out a clip to work around the problem (you can grab it from Thingiverse if you have the same issue).
I find that a lot of the printing I do is for problems like this - strange shaped objects to hold something in place or to join two things together that weren't designed to be joined. Previously I would probably have used duct tape, glue or rubber bands to achieve the same result - the printed objects make it much easy to disassemble and reassemble things though. If you were just using a printer for this it would be hard to justify the cost (although prices keep coming down) but with more proliferation of printers you are likely to know a friend who has one or have access to a Makerspace that has one available.
With tools like Sketchup and OpenSCAD freely and readily available making a custom design is not a problem and has no real cost (apart from time) associated with it. Even if you don't have a printer yourself you can still prepare a design for 3D printing and have it actually printed elsewhere.
The real value in owning a 3D printer comes in if you make any sort of mechanical objects at all. Having a printer makes prototyping (and even building single use designs) very easy and very fast compared to the other options. The image above shows a design for a stepper motor driven X axis I have been experimenting with - that was designed, printed and assembled over a weekend. If I had to do the same thing with 'classical' tools it would have taken me weeks or even months to get to the same stage.
Being able to prototype and test things so quickly lets you experiment with different approaches that you may not have considered previously. The object shown above was part of an experiment to see if I could drive a plotter axis with cheap bead chain driven by a stepper (the answer is yes, but not with a lot of accuracy). Without a printer I would not have been able to make the pulleys required to test the theory (and I went through several iterations over a single day with different diameters and grip shapes).
Having a 3D printer makes a huge difference to makers and small manufacturing businesses - and even for a casual user they can be a very useful device to have access to. Have another look at some of the low end to mid range printers available - you won't be printing 300W turbines but you won't be limited to spitting out Yoda heads either.