Representing Sweden is more lucrative for Duplantis than competing for the US would have been, and while he probably had no idea how big he would become in Sweden when he made the decision, he initially made it because the Swedish federation promised to take good care of him and he felt Sweden offered an easier path to international competition. So sure, it was a practical decision.
However, his mother, who’s also his coach and one of the two people most instrumental to his development, is Swedish and he’s always had dual citizenship. Choosing to represent your mother’s country, of which you’re a citizen despite not living there, is not the same as picking a random country just because it can fund your training. (Not that there’s anything wrong with that in my view.)
No matter what copium Americans are huffing, Duplantis is not just an American competing for Sweden. He is and always has been Swedish-American. Identity is complicated in this globalised age and children of international marriages have multiple nationalities. Deal with it and stop being so disrespectful to Duplantis, Osaka, Jacobs and other athletes; we all know you have no problem claiming ‘useful’ immigrants and children of Americans when it suits you.