Even if there isn't any gambling involved, there's a lot of planning and danger in transporting such a large amount of money incognito, which I think keeps the arc interesting.
I like this arc. Much more than the gambling ones.
It's hard to claim any skill from winning games of pure chance. The manga usually stooped to devices like "cheating", "uncovering how the enemy cheats", or, most commonly "Kaiji's indomitable gambler's spirit" (whatever that is).
All the victories in this arc are purely attributable to Kaiji and his friends.
... Well, except for
that extremely fortuitous encounter with an RV salesman who takes cash. Like, what the hell.