Yes... but what is to stop them from handing out your game to their MAC friends once they bought 1 copy?
Most people I know will pay for software even if they could get their hands on a free copy assuming they know the free copy is stolen. That in my mind is the real reason for copy protection, to signal to people that they're supposed to purchase the software, and for that the bare minimum (eg. input a registration code that the program stores in it's settings file) is all it takes. Meanwhile, the couple pirates I know (and believe me, I annoy them constantly with pesterings to purchase their games) aren't going to change their behavior because of copy protection.
A lot of it comes down to price point. At one price people will happily purchase a piece of software, but at some higher price they will pirate it.