Soccer is the number 4 or 5 sport for Americans, if it was even top 3 I'm sure the US would dominate every World Cup
US soccer players are the rejects of US athletes going up against the BEST athletes from around the world, think about it
You do understand that most athletes when taken out of their specified sport are average at best? Bo Jackson, Deion Sanders, Brian Jordan being the exception. Michael Jordan is considered the goat basketball player, but was terrible at baseball. Chad Johnson tried to play in the MLS during the strike and looked like an amateur against MLS players. Let that sink in. Chad Johnson an all pro in football not skilled enough for Americas reject sport.
Every sport has specific skills that a person must require. Hitting a 95 mph fastball, shooting 40% from the 3 point line, being able to run and catch while 300 lbs men try to tackle you. Soccer is no different. It has unique skills that only soccer players can perform at high levels.
As for your statement that if soccer was the 3rd most popular sport in America we'd dominate, how do you figure? Baseball is the 3rd most popular sport in the US and we don't dominate that against other countries.