Some people do, yes. Look at the people on here who own a 350Z just because it's different.
Some people just buy the best car for them, and to hell what others think.
The 570 would have to be a very special drive to tempt me ahead of a 911TT. It's not just the performance, it's also the practicality, and a 2+2 4WD sports car is a very practical thing indeed. That said, I wouldn't actually buy either, as at that price I'd be hanging off a used 458 instead. Bearing in mind options, you're looking at the McLaren being the wrong side of £160K I suspect.