Who is your idle skier? Let's just take Tom Wallisch as an example, a pro who is most defenit better then that kid. Just think of what Tom would have said if you saw you land that shit you are landing. He'd be cheering for you, happy that more kids are getting involed with a sport he loves. Actually, that would be the same reaction of the most of us.
Just remember, just because is better in skiing then you, doesn't mean is he happier. He has to put someone else down to feel better about himself. You should do the following 2 things.
When he talks shit, you start with telling hem that you are disappointed that he can't be nice. This puts you morally above him. And if he's not impressed, straight up tell him you feel sorry for him, that he has to put others down, in order to feel better about himself. But remember, it's not your job to give shit, so you are saying this in order to help the kid, not to put him down.
Which comes to my second point, if possible, become friends. If he's better then you, you can learn from him. You rather have him put his energy in teaching you, then laughing at you. Please note, that almost all kids bully out of entertainment or boredom. Giving him a alternative, helping instead of putting down, usually helps (I have seen this with my own eyes!). You achieve this, by constaintly asking him how to improve.
If he does not help you, coz he still hates your guts for no clear reason. Then you hopefully achieved a other goal, ignoring him, and he ignores you. I know this isn't always possible (if you encounter each other often), then all you can do, is disaprove his childish behavior. Look away, just laugh and shake your head.
My 2 cents