It is 10% at the peak of the estimates I have seen recently (last 12 months), usually more towards 7-8%. That is a very small minority. And, many of those users aren't gamers (who chose the Mac in the first place because gaming isn't important to them). You're assuming that those players wouldn't just dual-boot Windows or don't also own a PC... I assure you, many of them do. Content as in models, art, story, quests, etc. is shareable, but much of the actual client code (rendering, patching, sound engine, driver interactions, etc.) is not always shareable, and much of it requires minor changes even if it's mostly portable, not to mention further support from customer service, another round of QA testing, and an extra fork of development, plus coder time. It's really not a simple, easily quantifiable "10-20% effort", nor is it a sure "easily compensated" workload. "Boot Camp" is a completely reasonable thing to use. Dual-booting OS versions has been done for decades, be it from DOS to Windows, different Windows versions, or Windows + Linux, etc. etc. Your mac is just another PC with OS X loaded on it. I don't see how you can call using Windows "dumbing down" a computer.... it's only the vast majority (90%+) of the market. I also sincerely doubt most Mac users share your viewpoint of spending $80-100 for a Windows license being an onerous expense to add gaming, when you're already overpaying for the hardware by a margin in the hundreds of percentage points oftentimes. The Mac is still a tiny minority... google-fu is very easy to turn up proper statistics on this. And, as I already illustrated, it's not so simple as to say "X potential customers" especially with a mostly-production-oriented userbase as Macs have.