The reason why a lot of people bet with high amounts like this is because they are greedy, they might have probably had huge wins with small amounts of money in the past so they get tempted to use a huge stake to attract a huge reward forgetting the fact that gambling isn't really predictable. For him to lose 2.5 million dollars means that he must have gambled with highly significant amounts of money because no One can be stupid enough to use that amount on a single bet. It still doesn't change the fact that it was a wreckless thing to do.
You can only gamble this way if you know that there's a way to get that money back.You are right. We can bet such a large amount if we know that we will be able to earn this money again. If I am a billionaire, then 2.5 million is not a large amount for me. Even if I lose it, I can easily recover this money from another business. But when I have a total of 2.5 million, then I should definitely spend a maximum of 100,000 on gambling. Even personally, I will spend less than this on gambling. I personally have never spent more than 1000 dollars on gambling in a month. If I win at gambling, I spend this money on tours or buying gadgets. And even if I lose 1000 dollars at gambling, it does not affect my daily life that much.