User 'rdbase' has shared some details about his current position in the wagering contest two days ago. See this post to get some idea about the wager requirement for 4k to 5k rank at this moment. There are still 10 days left for the end of this contest. Therefore, you need to make at least $150k wager to enter and ensure your position in top 5k.

Currently my rank is 1700+ with $315k wager. Perhaps, I will stay in the top 5k at the end of this race. But I think I won't be able to stay in the top 2.5k users list with this wager.