Did her friend casually tell you about her salary without warning, or did you ask? I'm kind of curious about that. I'm assuming it isn't the latter, since you seem a little taken aback. If that's the case, I'm surprised that her friend would feel the need to tell you something like that. She really need to check her friends about that. It's not cool.
As for your actual question, I'd recommend that you try looking at it from another point-of-view to avoid that feeling of intimidation and inferiority. I think it's a matter of looking at them from a success-based standpoint than a monetary standpoint.
I, for one, like dating successful women. That doesn't just mean that they have high incomes, but that they know what they want in life, work hard, and reap the benefits. Whether or not the reap more benefits than I reap isn't the point. It's knowing that I'm with a driven and successful woman. At no point do I compare their success with mine. It's not a competition. It's just dating.