> But I guess that's not what makes it expensive
I went for a niche conference a few weeks ago which was held at a lower-end 'budget' casino hotel off the strip and the actual room price per night was more than 2.5 times the relatively reasonable-seeming room rate I booked under due to resort fees, taxes and other bullshit.
Don't forget that going to or leaving your hotel room usually requires walking through half the casino floor. Hospitality means something different in Vegas.