it sucks to hear about your friend's loss but it is common for an undisciplined gambler to become cocky or greedy(and your friend is one of them) when they are on a winning streak and that is one of the biggest flaws of an undisciplined gambler. gamblers who have patience, control and discipline would never lose all that in one day. that is why you have to stay cool and composed especially when you are on a winning streak.
- High self confidence.
- Bet with strategy
High self confidence, A gambler must have high self-confidence and more often known as the courage to bet. IMO If you bet a large amount of your money on one bet, then you will also have the chance to get a higher win. Big wins are for those who bet big amounts.
Bet with strategy, Gambling strategy is intended to get a higher chance of winning than without strategy. Martingale or other types of strategies are also a cause of great losses like this because you have to entrust your money to the strategy you play if you want to win.
I would not say these gamblers are the arrogant gambler category, but they can be said to be brave gamblers. Whether he wins or loses depends on his luck.