I don't like heights, but it's not at the level of a phobia. My first season riding, I didn't enjoy the higher parts of the chairlift and had to look at the horizon on those sections, but I've long since desensitized to that and I couldn't care less. Jumps still give me a bit of the willies, so I'm taking steps this year to desensitize myself to that.
Phobias are very real and can't just be dismissed as "weakness", but a lot of people who think they have phobias really just have a healthy instinct of self-preservation. You just have to convince your hindbrain that this is no big deal.