K-Dot.If they are a professional skier, then their profession is skiing. A profession is defined as 'a paid occupation, especially one that involves prolonged training and a formal qualification.'
So if they are being paid to ski, they are professional. Simple as that.
eheathA professional skier is someone who makes enough money to support a living without any sort of side job. You'd be surprised how many of your favorite "pros" get summer jobs to support their skiing careers.
yungFoolerSJOrange names on NS defines pro skier