What does this sentence mean?

It means just what you suggested it means. That you think it's an untrue statement has no bearing whatever on the meaning of the sentence.

Without more context I could begin to guess what the "weakness of American fundamentals" are. I'm guessing the author describes those in detail in the article.
The American dollar has not been doing so well over the last few years. It used to be the gold standard in currency markets. A bearish or bear market is a depressed or in a downward trend.
So... basically, according to this snippet, the author is saying don't buy the green back. Claims that it is a safe bet or a good investment are false, because American business practices?? are continuing to pull the dollar down. I think the author is looking for a total overhaul of the system or telling the smart investor to think before they buy.

thank you！