It’s honestly not that strange if you reframe the concept of “supporting.” In many ways, supporting a team equals willful suffering. It’s hard to embrace that fully if you’re coming into a sport/league as an adult trying to pick a team.
Also growing up in a culture/region where you experience firsthand team rivalries brings a completely different perspective such that it’s basically unimaginable to support certain teams. In contrast, from an outside perspective (e.g. an American fan), there’s no such baggage.
I grew up a huge fan of a team (São Paulo) and to this day I despise its main rivals (Corinthians). At this point I’ve lived in the US and have been following the EPL for longer than I watched the Brazilian league, but I have never been able to pick and stick with a specific English team. I’m partial to Leicester City and Liverpool (Leicester because I loved their Cinderella title run, and Liverpool because São Paulo beat them in the 2005 Club World Cup and also because I’ve enjoyed their gradual rise back to relevancy in the 2010s). So I guess I can say that I support those two teams, but not in same way or with the same fervor that I supported São Paulo when I was growing up.