The guitar some buy in threes because they can: Grote GT-150
Why buy just one guitar when you can buy three for cheap?
The above guitar is a Grote GT-150 in purple. It's a cheap single cut semi-hollow guitar. That's not the interesting part.
What's interesting how people buy these things.
I actually saw this below the listing:
Why would anybody do this?
It's mainly because of the type of guitar it is. Simple lightweight body with a nice finish, bolt-on neck and easy access to everything.
Out of the three, you can put yourself together at least two very nice guitars. Pick your favorite color of the three (I should mention there's also a green one,) and just take the best parts from each, modify them to your liking and piece together the guitars you want.
After that, you have parts to do with what you will. Want to try scalloping a neck yourself? Go ahead. Want to sand the finish off one of the bodies and try painting it yourself? Do it. Sand the neck and try a custom stain? Sure, why not? There are any number of things you can try for yourself when you buy three all at once.
The best thing about buying three of these is that all the parts on each are guaranteed to fit each other, meaning you're guaranteed spare parts without the need to hunt for them later. And that means a whole lot of freedom. Bang the guitar as hard as you want, because if something breaks, you have spares.
Ordinarily, I'm very anti-hoarding when it comes to guitars, but this is different. Three of the same thing allows for a lot of experimentation, customization and spare parts. And because these guitars are so cheap with no resale value whatsoever, throwing out what you break isn't a bother whatsoever.
Not a bad deal at all.