The grass is always greener.
Lexus wants to build a superluxury car. Hyundai and Subaru have designs on the luxury segment, and Volkswagen already sells a $98,000 Phaeton.
Luxury requires more than good intentions. Lexus probably can succeed with a $100,000-plus car. Lexus probably can succeed with anything it tries. But Volkswagen's Phaeton is having a tough go (849 sales in the first half). And Subaru and Hyundai are unknown luxury quantities.
It's easy to say, "Shoemaker, stick to your last," but that stifles innovation. A better warning is, "Automaker, look before you leap."