I believe this is referred to as a "fallacy of composition," or in plainspeak "an ignorant presumption."
I'll give you the benefit of the doubt though and assume you're trolling (and not actually that idiotic).
Not trolling here but I get the impression of some (not all) iphone users do in fact buy them just cause it says iphoneThat's why some had to get the bismuth pink last year (and why some with get the piano black this year): they have to prove they have the latest and greatest to everyone.