Why do the cell phone companies do this?

I wanted to get the Droid for Christmas so i went to Verizon to check it out. I had just had my newer phone stolen so i had to use my upgrade to get another one. They told me that in order to buy the Droid and purchase unlimited Internet for it, I would have to pay a $150 cancellation fee for my current phone (for the new plan), and a $150 upgrade fee (because my upgrade had been recently used). Or, they said, I can wait until August for my upgrade to come. I think this is ridiculous. Don’t they realize that they are just delaying my paying them? I doubt anyone would pay $500 for a $200 phone, so why do they try to charge it? Why so they think I wouldn’t pay the cancellation fee to switch to AT&T? At least i could get an iPhone for Christmas. I don’t understand how this company thinks at all.