In order to see yourself as a candidate for an olympic medal, at ANY sport/event, you're going to need an astonishing level of god given talent, years of preparation to perfect your skill, personality traits (resilience, persistence and an obsessive drive to win) and LUCK.
However, it goes without saying that in order to win a medal in the 800 meter run, you're going to need to be one heck of an outlier - in all those parameters - while athletes in other sports have a much easier route.
Parameters that weight into the equation:
1. Depth of participation and entry blocks (every kid gets a try at running, how many train at sailing?)
2. Variety of events spreading the talent pool (imagine multiple track events, e.g. "800 meter skipping")
3. Multiple Events (It's like that old thread about the "three things challenge". It's always harder to be the best at one specific skill).
4. Rules of the event (at the Olympics). Take Taekwondo for instance - you win 2 battles, lose 1, and you might still find yourself in the final. So Get Lucky.
Any Olynpic Medal is an amazing personal accomplishment, but All Medals were not created equal.