Why Custom?
Custom keyboards are definitely not for everyone. While custom computers are often cheaper than a pre-built one with the same components, custom keyboards are far more expensive than the off-the-shelf variants. If your standard keyboard on your laptop or work computer gets the job done, it doesn't feel very nice or look very good. These are the Honda Civic and Toyota Corolla of keyboards. They get the job done but aren't particularly flashy or personalized. Gaming mechanical keyboards are like the Lexus, Mercedes Benz, and BMW of the keyboard world. They are designed to be nicer and be far more accomodating with features that most lesser keyboards will not support. They also perform far better. However, custom built keyboards are very much the Rolls Royce, Bentley, Ferrari, Lamborghini, etc. of the keyboard world.
YOU are the one who picks the color scheme. YOU pick all the parts. YOU will have a keyboard that is YOURS and may not have an identical one in the world. In addition, some of these keyboards gain value over time. These custom keyboard have a FEEL, SOUND, and SATISFACTION to them when you type on them that normal keyboards do not have. While it is understandable that nobody normally would think building a $300 keyboard is a good use of money, I would beg to differ. You don't need to build more than one of these, but if you are someone who spends a good portion of their day at work or otherwise at your computer typing away, such a custom keyboard might just be the one thing that makes your work more enjoyable and keep you sane during days when work is just too much or you are just having a bad day.