Not a word of sasrcasm. Recalibrate your sensors.
Screw 'em? The world? That's the rational approach? I will not pretend anything, nor will I surreptitiously use hidden text to put words in someone's mouth.
"something best for you" is subjective. It can be safely assumed that the people buying Beats over aurally superior price comparable headphones aren't highly motivated by the sound. So what is best for them? The respect and admiration of their peers probably figures quite high in that. And hence it is a totally rational decision. Doing the thing that accomplishes the goal is rational.
If you think the goal is irrational, well fine, but most of the world exists as an aesthetic, and people do care about style as in indicator of taste, prosperity and status.