Yes, people that actually compete in events have a better chance of winning. That's just the nature of things. What you can do to even the odds is apply for a position as an event coordinator and host events in your time zone, if you are able to get enough people interested.
Bigger clans do have a better chance at taking more top spots. But you're looking at this incorrectly. These aren't team events, so it's individuals competing. You can't penalize a clan for having more members. Solution: Form or join a bigger clan.