I remember in the 70's, there was 1 guy in vegas who set the lines for all the games. He was super accurate but later died. It was a crap shoot after that.
My ex brother in law is/was a big gambler with all his theories on gambling. I know many believe that they set the line so they get equal betting on both sides so they can make the juice. According to my BIL, he said that is what they want you to believe. The juice money is peanuts to them. What they want is for the betting to go all one sided and win the big bucks. Most bettors make poor choices. That's why gambling so hard to win consistently.