In years past, before the illegal immigration invasion of the 1980’s (which hasn’t stopped), America largely ignored Soccer. Due to the general wealth of the USA, Americans enjoyed numerous other sports, all of which require a bit of money to play with equipment costs, uniforms, specialty grounds etc...
American’s also enjoyed boxing and horse racing. Tastes change. Baseball has seen a massive drop is popularity and has been forced to import “third world” players to offset that.
Third worlders in baseball is due to the fact that Pro teams can exploit them from youth in their home countries. They don’t even go to school at all, rather just raised to play baseball in organized baseball schools run (paid for) by MLB.