Has that person lost a physical disk?
No, all he *potentially* lost was a *potential* sale.
Many 'pirate' downloads often lead to real sales.
So a 'pirated' version does not equate a lost sale per se, it could actually even lead to a sale they wouldn't otherwise get. Try before you buy principle. I can spend my money only once, and I have to make decisions whether I want to buy a certain entertainment product or not.
And some companies offer demos, but more often than not, those demos contain only the best pieces, and don't show the crap that's the rest of the content.
So if I can taste the full version before I buy it, I can make a more informed decision on whether the product is for me, or not.