Nothing beats the thrill of seeing a shark!!!!!! o my......
Well seriously now. They bought the sharks to bring people in and be like "ohhhhhh sharks, so coo l!!!!!!!!!!!".
When you first saw them in the tank, you probably watched them and thought thats cool. Then your aquarist brain kicked in and said this is wrong. I bet you most the people that go in there dont even have the thought of " oh my those sharks are gonna get huge and I feel bad for them". Hell, they probably have people just coming into the store to see the sharks. Its good business smarts on them. Get people in the store, maybe they will think fish are 'cool', and then they spend allllll of their money.
Oh and PS.
If you want to be mad at big als about the sharks. You should watch the documentary on shark finning. Then you may be mad for other reasons.....If your curious and have the stomach for the cruelty just youtube "shark finning".