Well first of all, this is the OLYMPICS, there is really no "public money" to factor in here! Only serious gamblers would even know where to find lines on olympic events.
Also keep in mind that Spain played in an easier division than the US. Shooting over 70% from the line as a team is not that good. Better than the USA, but they dont win from the line!
I do agree that they have more motivation, but now that it is single elimination, the USA will take it seriously and win the gold medal with relative ease in my estimation