Chances are, you’ve never eaten authentic wasabi. What’s usually plopped on tables at Japanese restaurants is a blend of horseradish, chinese mustard, and green food coloring.
Authentic wasabi is difficult and expensive to produce, making it unsuitable for mass export of Japanese culinary culture (though, to be fair, most people in Japan end up eating fake wasabi, too).
That said, while apparently the real thing is quite extraordinary and not just “ohmygodthehotthehotthehot,” if people eat the substitute enough, it becomes a legitimate alternative foodstuff of its own. Just … don’t think it’s the “real” thing.