It's tough to say what the odds of winning anything even are-- prizes are only available to US residents.

There were 154,153 entrants, but only 143,061 recorded 100 or more miles.

Of that number, only 51,673 are from the US. I finished 1,464th.

Then you start looking past the raw numbers, and there are people who supposedly rode 2-3 times per day, and you wonder what kind of verification process is in place.

And personal issue here: the 1st place guy on the leaderboard did a 693 mile ride around the Finger Lakes in NY. Problem is, with a 38 hour moving time and a 79 hour total time... umm, that's not one activity.
Sorry. No one on a bike tour just pauses the computer at night and starts it again in the morning, and then calls the whole tour a single activity. His Move Ratio was 0.49. That's four rides.
Yeah, they're big ones, but it's still four rides. One of the "breaks" was 11 hours long.