Welcome to the forums, do you plan on adding the Z650 to the stable, or just getting rid of one and getting this ?
While we wait for a response often I find people in this segment just own one bike, the bike being talked about. It's the bike that does it all. As you go higher up thea CC's then the odds of a second bike increases.
It also has to do with demographics, usually those guys on the liters are a bit older, more experienced, higher income, etc. So they have more room to play around with other toys. And odds are they aren't married so no wife to yell at you for having multiple toys while you still haven't bought her that C-Class sedan