Definitely crazy especially when you are someone who is not even earning what he is betting. If you think about it, $10k is an amount that a lot of people myself included would not even think to gamble. If I had $10k, I would use it to pay bills and buy myself some good investment properties. Even if you tell me that I can double it, I am not in the socioeconomic class to spend this much on gambling 
Me neither, but as they say, someone's lunch might cost more than someone's salary. On one side, some people might not be able to imagine spending that much money on gambling, and on the other side, someone might be having fun with that amount because they might have substantial wealth and this amount might not even make a dent in it.
We will never know if that user is doing this only for fun or maybe he is also making money through this. Maybe some people just loaned this money and they are using it to gamble. There are always backstory in all of these.
It's understandable if someone is spending that much money on gambling if they can afford to do it, but if someone is doing it to earn money and the money has been borrowed, that is a very bad idea because gambling can often times be brutal to gamblers. We have seen and heard of people committing suicide only because they lost more money than they could afford in gambling.