Why do i pay casino employees' "salary"?

I wrote about this before. I play Video Poker in the bars. If I win the Bartender expects a tip off the winnings. I don't understand this! What did they do to help me win? I tip on the drinks they serve me (I tip well for the drinks)... Shouldn't it work both ways..If I lose shouldn't they give me a few drinks?

LOL...I experienced that in Vegas a few years back.

I was leaving the Sahara, and had a few quarters in my pocket. I dropped them in a slot machine and won $400. I called the attendant over, showed her the machine, and followed her over to the counter. She gave me the cash, and then stood there waiting for a tip......