I don't get the food analogy, you have to eat food to survive, but you don't need to drink beer. On my own dime, I'd simply not have a beer unless it was something higher quality than BMC swill.
The big thing that I haven't seen anyone mention, simply comes down to variety. I don't have a problem with folks who drink BMC, but, doesn't it get old? I'm not talking about some of the folks here that may mix it up with craft beer and BMC, but the guys like my father-in-law that drinks Coors light exclusively. At home I keep 4 homebrews on tap, and always have anywhere from 6-8 different craft beers on hand in the beer fridge. When I decide to grab a beer, I have a lot to choose from, and switch things up. This is the best part of being a beer drinker/brewer today. I couldn't imagine being a BMC drinker that drinks the same exact beer over and over and over again.
This is really no different than any other hobby. Some just drink beer, some make it hobby.
One of my other vices is stereo and home theater gear. It's no different, really, Some just listen to music on a boombox and enjoy it, some have 12 pair of speakers, a dozen or more different amps and receivers, different DACs, a few different CD and DVD players, tape decks, turntables, etc. and still are looking for the holy grail.