Of course, they were likely complying with fire laws (and with equipment that probably complied too), and since the MGM fire years ago these matters are taken quite seriously, as they should be in any structure where sleep-deprived and sometimes drunk people are sleeping very soundly at all hours of the day and night.
Long ago, I was awakened on the morning of my last day in Vegas, with a flight scheduled, as I recall, for around 11am, and with the alarm sounding at, as I recall, around 5am. Needless to say, with that volume, I couldn't get back to sleep, and so I showered, packed, and went down to the casino for one more session before checkout, and I scored a nice win - which I considered to be "justice" 
Hope you had a similar compensation for your suffering.
--BG
ยทยทยท
======================
9. Fwd: Its Alarming !
I sat down at a 9/6 DDB thief and almost at once a
deafening blaring staccato sound filled the already
noisy air. That was followed by an equally unbearable
distorted voice. It was a warning of an impending simulated
fire drill. It just kept on repeating and repeating at short
intervals. Both myself and the lady next to me had to stop
playing to cover our ears. I mean mine started ringing. I
called over a guard and he agreed the sound level was
waaaaay to loud. I told him instead of testing the alarm.
they should be testing the SOUND system first!