I don't drink that much.
Don't worry, you will.
Even if you have only four taps, you may wish to have additional storage for aging or kegs waiting for a tap to open up, especially if you don't drink much. That way you can brew when you want or have time, instead of having to wait until you are almost out (that's when I inevitably run out of beer).
I have a keezer with room for four on the floor. I am currently debating replacing the 2x6 collar (I used pieces of a redwood bed frame that was sitting in my alley at the time) with a 2x8 one so I can jam one or two more kegs in on the compressor hump.....even though I may not increase my number of taps.
Or (what I really want to do) is get a second chest freezer to use as a ferment chamber/aging cabinet or a humongous one to fit all the beer I want.
I actually almost bought a beat up commercial back bar bottle cooler (8 ft. long monster). Guy wanted only $100 for it, and I passed cause it just was too big (wouldn't even fit in my van)....and I have been kicking myself ever since....
Although, I didn't have to justify the purchase with my wife...so I live to tell the tale.