Define "popular."
As the old saying goes, in the United States, Soccer is the future of American sports and always will be.
Someone makes a unimaginative remark (Soccer is boring) and of course it's perceived as an insult to other posters heritage, family, physiology, and intelligence. Hence, we get these little tete a tete strings.
Face it, soccer is not "popular" in that a plurality (say 30%) of American sports fans could properly describe the geographic space on which the game is played. (I believe they call it a pitch) OTOH, I suspect that a substantial majority of Americans (not even sports fans but simply those who watch enough TV) could rattle off the names of 10 players in NBA, MLB, or NFL. Conversely if 1 in 10 American sports fans know the name of a current soccer player, I would be surprised.
It's not an attack nor an insightful observation that most, as in a majority of American sports fans, are uninterested in soccer. You would get the same response if something was posted about celebrity or royal wedding, it is not something American sports fans are going to interested in, and usually that will prompt a bit of snark. It is what it is, learn to get over it; and maybe appreciate that while you may be an idjit, at least you know the difference between a baseball pitch and a football pitch. (You can fulfill the need to be superior to something or someone!)