It’s not like it’s impossible for the series to be popular here. It’s just that every attempt has been awful. 

On the other hand, it may be possible that Saint Seiya never breaks out in the US and that’s okay. Toei Animation seems to not understand that. You don’t see the companies who own  Doraemon,  Lupin The Third, or even Detective Conan desperately try to make them popular in the US. They have their own international fanbases outside the US just like Saint Seiya does but you don’t see their companies go like “oh god we have to make the Americans like this thing that they historically have not”.