me on dvorak: 110 wpm (10-race average) on typeracer.com
If your typing speed is high percentile, odds are you'd be faster than all your friends anyway, regardless of dvorak / qwerty. (E.g. I type faster than every single one of my qwerty friends! ...)
Given that <0.1% use dvorak, there's >90% chance you won't see a single dvorak user in a random sample of 100 people. Not hard to see why the leaderboards will be "dominated" by qwerty.
Like others have said, dvorak is for comfort, not for speed. Dvorak is MUCH more comfortable than qwerty.
Also, Dvorak users almost never complain that they type more slowly than their qwerty days, once they've gotten used to it.
Many of us dvorak users also are competent at qwerty in a pinch (80 wpm qwerty here).