I disagree.
If nobody was nonchalant, the word would not exist.
And no, 'nonchalant' does not mean you don't rate people. It simply means external pressure does not disrupt your internal equilibrium as easily as it does with most people.
You have a much higher threshold for emotional activation, which means the degree external events have to reach before they provoke a disruptive internal experience is higher than average
It also does not mean you don't have or show emotions, just that you 'feel' less frequently and less intensely than most
Whether that be when the love of your life cheats on you, Messi scores a winning goal at the world cup, or you lose your X account at 50k.
And this has as many benefits as disadvantages, but that is a tweet for another day.
Nonchalant people exist same way neurotic people exist - but on opposite ends of the emotional reactivity spectrum.
The confusion is that most nonchalance these days is performative. If you met an actual nonchalant person, odds are the word you would use to describe them is psychopathic