If the fork does not happen the price of BCU will go to zero. Buying BCU is a way for you to bet the fork WILL happen. If you bet on a horse to win and the horse does not win then you lose your bet.
Same thing here.
Only buy BCU if you think the fork will happen (or you think you can dump them for a profit on some other sucker that thinks the fork will happen).
I still wonder why People opt to buy BCU coins while knowing fully well that a Bitcoin hard fork is under probability and may not happen. Seems like a top gamble. My thoughts are that, BCU coins aren't worth those predefined values by Bitfinex