Having a lot of money does not really determine how well you would be with your gambling habit, because sometimes these money you see to be really big might be what these rich people see as as small enough for them to just throw at the casino and if it doubles up they go happy but if doesn't they have no problem with it.
I think what really causes this has to be self control, if you have good self control, you wouldn't have to moderate yourself if you have got enough self control and a lesser greed, but then I don't think these people Play with such big amount because of greed rather it's basically because it's what they can comfortable afford to loose.
These high rollers have different approach with their bets because they can afford to place big ones.
And they won't stop up until they have funds to supply their gambling activities and satisfy their desires.
Most of them don't care about losing those big amount of money, so no one should follow their footsteps if you can't afford such gambling lifestyle.
And some of them are popular personalities where they are bragging those high bets on their social media, so we also don't know the true story why they are publishing it on their social media. Who knows some of them are also being paid the casino itself?