Do there exist any studies on how much money people actually spend on pure status pursuits?

I don't know but I also think that such studies would have major problems with data. In a way, whether you're buying utility or status is about intent. Let's say I like fishing and want a new boat. I can buy a 12' boat or a 18' boat. The 18' one is more powerful, convenient, but also more expensive. It's also bigger than my neighbor's 16' boat. I pick the 18' boat -- how do you determine which role my desire to trump my neighbor played in my decision to get the bigger one?

In practical terms status competitions seem to take off when people have nothing useful to do with their money (aka once they personally pass into post-scarcity era). Or, of course, if they really want status.

Look at what Russian oligarchs are buying. Look at what the Chinese are building (see e.g. http://edition.cnn.com/2013/07/24/world/asia/china-government-building-ban/?hpt=ias_c2). Do you think Dubai built its tallest building just because they wanted so much office space on so little land?