I have started to chase them, currently still in number 5, I don't expect too much, being able to occupy rank 10 I feel like I'm already ahead, because I really know who those who are below me are, especially Gennady12, he will definitely make a brutal bet in the last hour

Those user with same level of wager amount as yours will surely chase you, Not only Gennady12 is your problem if you want to secure that spot.
You should start increasing your lead earlier so that other user will be discouraged to wager more just to chase you since the rewards is slightly lower now.
Even I can still chase the top 3 within an hour period if I will commit on this tournament. If the 3rd place didn’t move I will try to start wagering already.