Pretty much.
One of the Dallas-Pittsburgh Super Bowls back in the 70s was famous because it opened with the Steelers as 3.5 point favorites. The early money was heavily on Dallas, so the casinos dropped the spread to 2.5 points, and the late money was just as heavily on the Steelers.
The Steelers won by 3. So, the house paid everyone who had Dallas plus 3.5 points, and everyone who had Pittsburgh minus 2.5 points.
The sports books are a lot more sophisticated these days, and don't give themselves that sort of exposure.
And all the prop bets. That’s really where the cash is these days. There’s so much volume in those any minor short comings on a couple lines are easily covered. They especially love those trifecta stats bets, those 10,000 to 1 odds lure so many people into bets that almost never break. Probably only 1 out of a million actually ever win those, which puts the house ahead 990,000.