So, it doesn't matter how much you wagered individually, there is no fixed amount required to be the top one, like say there is no 2 mbtc requirement or anything to get picked type of deal.
There is only requirement to be the highest wagered person on that round and you will get the most chance, you don't even have to be the highest wagered person in that hand to win because everyone has a chance to win but if you are the highest wagered one you have the highest chance, doesn't matter how much it is, if you wager 0.3 in a round where everyone wagered 0.25 then you can still be the highest wagerer. That is not bad at all, it gives people incentives to beat each other instead of trying to beat a set goal by the website, if you tell people 5 mbtc is the requirement they will just use 5 mbtc and stop, but if you tell them beat each other than there will be fight to be the biggest eventually.
I don't think if the player who has the highest wager will have a chance of getting a big jackpot compared to other players below him. It does not depend as happened in this game on this mini jackpot it looks like this player gets a high jackpot even though he only has the second-highest wager. But why did he get a big jackpot? that's because he also has the biggest payout among the players.
