mining is fun. how many people buy a $200 box of lego, spend 2-3 days assembling it, and then put it away on a shelf as a decoration? setting up computer gear is fun for some people.

you can blow $1000 gambling for a few hours of fun in vegas and walk away empty-handed.  Some people like me would consider bitcoin mining as a bit of a hobby, particularly one that can make a bit of profit if things go well. not many hobbies make any money.

also, mining depends on your outlook on BTC. do you see it at $1500 or $150 by the end of 2014? Its going to be at one of those extremes, and my money is on it going up (literally). I don't think its hard to envision a near-future where huge facilities hosting 10-20PH of power are located all over the globe, run by both private investors and/or banks and investment firms who want to produce their own bitcoins.  If bitcoin continues to be the leading solution for a future-proof currency it will be very valuable in 5 years from now