AITA for refusing to split a $500 raffle winnings with my gf?

My girlfriend (22F) and I (22M) of 1.5 years are on vacation with my family and we go to a cornhole tournament with my cousin. At the event there are a few raffle boards where you can buy a square for $10 a square and the winners can get various prizes. I bought 1 square on 3 different boards for $30 total, and I let my gf pick the spots were she would write down my name. Time goes on and somehow I end up winning the $500 board.

To give some background in our relationship I pay for 80% of the expenses in our relationship, ie. going out to dinner, activities ect. and she then pays for the other 20%. However, when she pays she uses her parents credit card and not her own money because her parents can afford to do so and she is a college student.

Then after I go up to collect my money my gf says "oh so were going to split that 50/50 right?" To which I respond "umm no I don't think so". She then continues on to ask me to buy her new shoes or new jeans with the money that I won, then finally she says that I should put the money in an account for an engagement ring. I again refuse to do any of those things and respond with telling her that I will pay for the drinks and food for the night, then take her out to dinner a different night.

I also have to add that almost every time that I "gamble", ie. buy 50/50 raffle tickets, play slots, sports bet, ect. she responds with something along the lines of "you shouldn't be wasting your money on that you should be saving up for a ring" It seemed kind of cliche to me that when I win money from "gambling" she wants 50% of it but when I lose money she says how I shouldn't be wasting my money. AITA?