My colleague and I work at a small company as software developers for Windows. It is a fine job and we have fun and create great software. But as soon as I leave the company I become a Mac user and developer. For some time now I am trying to get my colleague interested in Mac development too. Because working with your coding buddy is so much better that to do it alone. But I have admit I am not very successful convincing him. Still he has no Mac but money is not the main problem. He always tells me things like "Have to learn so many new things" or "I don't' want to do both. I want to do one thing and be very good at it." He is coding in his spare time too. But for Windows only.
I can only say my experience as Mac developer made me a better Windows developer because you learn about so many different things and get many new ideas. And I am in the business for almost 20 years now. Also the iOS development is great. You can operate software with your finger - how cool is that?
Yes, my colleague was impressed. But all these arguments are still not enough to convince him. You got any more ideas?