I've been to Vegas twice in my life and one moment on the casino for stood out.

My wife and I were just doing some slots for a bit and a lady behind us (who seemed like a regular) hit a jackpot. Lights and sirens were going off and a floor worker had to come over and do something to finalize it. The whole time she just sat there, hardly any reaction. The worker congratulated her and moved on. Then without skipping a beat she just went back to playing the slot machine like nothing happened.