Why do Argentinians love Decathlon so much?

Today I went to my local Decathlon in Florianópolis and the proportion of Brazillians to Argentinians was literally about 1 to 50, and there were temporary signs put up with translated information in spanish.

Locals know this happens basically every year, is it because there's genuinely nowhere to buy sports attire in Argentina, or is it much cheaper here, or both?