Because the parts of the economy providing food and housing take up a small fraction of the total work available to be done. The rest of the work (ie surplus) can go to one of three things:

1. "Storing food for the winter". R&D to prepare us for challenges we'll face in the future. Ex: alternative energy research. This sort of thing is extremely difficult to fund in a capitalist society. We need more of it.

2. Waste. Accounting and lawyering and sales and such.

3. Entertainment. Everything from movies to luxury goods.

If given a choice between 2 and 3, I'd pick 3 any day. I'd like for there to be more of 1, but I guess that makes me a socialist :).

I don't see any functional difference between a Farmville cow and a ceramic cow that sits on a mantlepiece. They have exactly the same practical use, but one cost way more energy to produce than the other. My argument for how Farmville will save us from global warming is a post for another time.

tl;dr: Value is what the market says it is, not what you say it is.

See also: http://www.slate.com/blogs/moneybox/2011/12/12/let_them_eat_...