The need to reassure themselves that they are doing well and to announce it to the world. That's why so many luxury goods announce themselves by a big logo; the standard Louis Vuitton bags, for example. Now, I have never felt the need to advertise some product . If I buy an LV bag, I buy one which is definitely not standard, so it doesn't advertise Louis Vuitton , with LV all over it. It's there as a bag, not to tell the world I have paid X thousand Swiss Francs or pounds for it .
Ferraris? If you like that kind of car, that's what you like, but the show- offs always buy the sports models . You never see one in a saloon; nobody would know they'd got a Ferrari !
70 inch telly? Only person who needs one is someone in the film industry, and it is for their spare room !