Untrue, Mac users are growing. Also Mac's are not bad for gaming as the hardware in them is usually fairly good for the video editting and 3d rendering software that is used on them.
Mac users are growing, but many of them are not running Mac OS on their machines.
Every year there's an industry stat put out for what computers are using what OSes
Mac OS was 5% last year
Linux was 7%
The rest was Windows with a few percentages lost to more obscure OSes