There is no doubt that the popularity of the sport can be partially attributed to the very low cost of the gear needed to participate. Essentially all you need is a ball. You can make everything else using whatever is on hand.
The dominant powers in the game are primarily rich European countries. Even Brazil with the world's 15th largest economy can't be considered poor. Six of the eight in the current WC quarterfinals are from Europe plus Argentina and Brazil.
In contrast football and baseball have stronger high school and college offering. I think another poster had it right that many other countries just don't have sports leagues like the US: NASCAR, NBA, NFL, but they do have soccer, so they focus on that sport.
Interested in your thoughts kabar and AGP.