Although it does seem like pros are always making it to the final table, I'm not so sure it's always the same ones. I have seen a few pros have a couple of good showings over a short period, and then not heard anything about them for quite a while.
One reason I think pros tend to have deep runs on a more consistent basis is that they have less of a tendancy to want to get all their chips in the middle. Where amateur players pick up a big starting hand and are willing to ris their stacks pre-flop on two cards, most pros seem to avoid being all-in if they can help it.
Another reason I think so many pros frequently manage deep runs is that most amateur players have have a lot of respect for (fear of) them. I was playing an S&G one day when one of the other players mentioned seeing that I was registered for a $110K pro bounty tourney. That person's advice to me was to fold anytime a pro raised or 3-bet me. Dude, did you say scared? Not me! When moved to a table with Annette Obrestad and Melanie Wiesner, if I remember correctly (can't find my pro list right now), I wasted no time in showing them that I was willing to play right back at them. With me showing a complete lack of fear and a top ten chipstack, it didn't take them long to figure out, being pros and all, that they had to respect my shit.
Every player has dreams of being able to go up against the pros and hold their own. But given the opportunity they average player is going to shut down and get run over until they're in the position where they have to shove any big hand. Meanwhile the pros are making moves and building their stacks up. The game gets a lot easier when you're playing for all of the other guys chips, not all of your own.