Does your girlfriend's daughter have friends who have the same level of success?
Maybe it's normal in her circle to share that kind of thing. Most of my friends aren't that wealthy. This is a small sampling of things my friends post about:
Lots of my friends post cute pictures of their cats or dogs or their kids or grand babies and funny jokes and honest accomplishments anyone would be proud of, not bragging really. A lot of my old classmates post songs we all loved and sometimes pictures of us they found in some old box in their mother's garage and we all laugh. They post about this crazy winter and how tired they are of it. Then I have my old friends from high school who post how much they hate Obama or the ACA and all kinds of tea party garbage and how heartless they think our country should become. I have friends who post about how they hate religion and how stupid people are for believing in God or gods. I have friends who post about GMOs and how marijuana should be legalized and how it cures every single thing that could ever go wrong including cancer and no sir it is not bad for your lungs, nuh uh. Cute No one brags about BMWs, though one of my successful Italian friends is always posting pictures of him and his Italian brother and dad baking home made pizzas and fabulous pasta dishes from his amazing, very expensive looking kitchen. I have another friend who had a foodtruck custom made and she and her brother cook and then drive the truck around Charleston, SC serving delicious cajun cuisine to the locals. She also posts pictures of really cool and often sexy shoes she would love to have. She also posts the best blues and soul music links. Then there are the bitstrips. Don't get started on the bitstrips. They can be addictive at first, but they are fun. I have one friend who is into learning self suffiency with her husband and she posts really cool things they are doing or learning to do.
I post a lot of pictures in my fb albums for my kids and me so we can look at them easily. It's a great place to share things like pictures of your container garden that is bringing you immense joy. Then there are the garage sale/thrift shop finds, etc.