From what I know, Franco beat Serge in 1973. And in 1974 Serge will not compete.
I think Arnold earned his car and house . . . And we need to ask ourselves why Sergio had to work? I would suggest he had offers from Joe and perhaps Dan Laurie. Why did he not capitalize on opportunities?
J
Or ask yourself why Sergio was forced to make money elsewhere, from Lurie as you said. Why Weider was not as generous with him (as it was with Arnold, a newcomer).

Weider decided Sergio's fate by bringing Arnold to the US. I think no one is naive to believe anything else. As himself said, he invested too much in Arnold, to be only the 2nd. It was a matter of time.
If you look at pictures from the 1969 Mr. Olympia, you can see on Arnold and Weider faces their disappointment..It was too early. And Sergio was too good.
A year later, at the Mr World, Joe and Jim Lorimer had tricked Sergio to compete saying that Arnold will not appear. Sergio was not ready for Arnold. He still had 2 weeks until to Olympia. It was the perfect opportunity for Joe to show that the invincible Sergio can be defeated. And Arnold to come at the 1970 Mr Olympia with the image of the guy who had just defeated Sergio, the champ.
But it was not enough. At the 1970 Mr Olympia, to be sure of victory, Arnold tricked Sergio saying that he is tired and wants to leave the scene. Sergio agreed to leave the scene, but Arnold remained alone making gestures," why Sergio gone? I'm still here." And so history was written..