Ah, now I understand. You're saying that it's fallacious to believe that an upswing will necessarily have a downswing, and vice versa, is that correct?
What I understood (due to hastily coming to conclusions) was it is dangerous to believe that life has lows and highs.
That's right, but it's also important to realize that, in fact, there is no grand narrative[1].
Humans are compulsive pattern-recognizers and can turn any arbitrary independent sequence of events into a story.
That doesn't mean the story is wrong, per se, but it does mean you cannot presume to know where a story "is leading up to". Because the only "complete" story is the one that is told afterwards.
What I understood (due to hastily coming to conclusions) was it is dangerous to believe that life has lows and highs.