We have seen huge multipliers on rollbit where player have wagers $3-$4 and they have win $3-$4k easily so this is not a big amount compared to them.Beacause he is already wagering $35000 on single bet and he is quite lucky to win on that bet with million dollars which is quite a huge amount.There are some players who are actively engaged in gambling and don't care about lossing because they have built mindset that bet high win huge or say high risk high profits.The list is long for such players but as said by you that he mostly wager $1000 on each bet is high somehow but still depends on the player how he wants his fund to be managed but on the contrary basis it is your luck which matters the most of you are playing dice, roulette types of games.