Why are people buying expensive cars, clothes, ...?
Of course you could buy a Tudor or Breitling with a "refined" ETA 2824-2 movement for 3500 bucks, or you could spend 500 bucks on a watch of the same quality with the same movement (except maybe a different engraving on the rotor). Only difference is how much they spend on marketing. Again, same with any luxury item. I'm only buying Swiss/German made watches myself, but if I'm completely honest, the best watch I've ever had all in all was a $300 Seiko. It's not exactly rational.