Most likely this is a secret, but still Ill ask. Are there any setups for automatic dice to stay in a small minus, but wind up the volume for the competition? But most likely whoever uses this just will not tell me

No, there's no secret. It's called a strategy which they come up at the very last minute of the contest.
It's about the bankroll that you have and most that has bigger bankrolls has higher chance of winning not just gambing alone but also in the contest.
There has been a lot of talk about a lot of possibilities of increasing the volume without losing too much but in the end whatever method you use its going to end up with 1% house edge possibility, all you can do is to make sure you lose that amount instead of too much.
Just to give an example if you gamble with minimum for too long with highest possible win odds then you will have played longer and have a higher wagered, if you gamble 5 btc all at the same time than you may either win 5 btc or lose 5 btc and end your quest for high volume. So, one is riskier with higher reward, the other is guaranteed loss but at least guaranteed better chance to have a long wagered with less risk of losing all your money. There are plenty of methods to try and test for it, not all works and in the end its all luck.