I've hustled my brothers out of nearly 15,000$

I go to a pretty expensive private school, and I am about to enter my second semester of my junior year in college. My second semester of my freshman year, I join one of the biggest frats at my university. The dudes from the frat are so nice, some I am not to close with but the ones that I am close with are like actual brothers to me.

Thing is, they are all stupid rich, and don't really give a crap about their grades or anything, but they gamble like crazy. At first I was scared of losing money to them, but over time I realized that they kind of suck, I mean I was no better, but they all played a crazy amount of poker, and played super aggressively, and only while dunk or high, and with a lot of money. I'm talking 200 dollars to buy in minimum.

For me as a freshman that was a lot of money given that I don't come from a wealthy background like them. Well, I started studying poker a lot more, I used stuff like preflop wizard and eventually got to a point where I would clean house anytime they played me. What's crazier is that they would keep playing. I would walk away from our poker nights with a lot of money some nights I made 500$ which is insanity.

I feel really bad for taking their money, but its been keeping me afloat in college with paying off my loan interest month to month, but taking advantage of them like this make me feel weird.