This kind of event only serves to increase the overall trading volume. So, apart from you having to reach a certain trading volume for eligibility, there is competition between traders after that. Let's say in terms of a $50k distribution, the $10k reward goes to the 20 traders who hit the highest volume, and the rest goes to the 100 with lower volume.
If you only chase the eligibility point, you will only get the smallest reward or none at all. I think there is nothing wrong with the event, it's just that you miscalculated or had high expectations with your small caps.