Okay I've had three contests so far and they have all been the casino ones. Is it a bug, terrible RNG, or they haven't added any others yet?
Nah others have had different contests about spending energy and stuff, but the distribution is pretty weird I agree.

Does the box reward depend on your rank? I just got a white robot that's worth nothing, I'd gladly pay a million for a legendary. Btw how many points did you get? In my current contest #1 is 278K, and there's still an entire day to go.
From what we can learn in that thread, the reward has nothing to do with the rank, some guy got a common pair of pants for finishing first ><

I think I have an explanation for the ridiculous scores of the leaders though:

I passed a German in the last 30min with 190k points, but since these dumb casino contests overlap I raised up the stakes for all the other contests. Next one is like yours, 260k in one day, I suppose the guy did the same thing as me, it's the points he grinded to win his previous contest.

People Like you and I who got several casino contests will make it really hard for newcomers.