Why people feel compelled to minimize the shittyness of Trump's family is beyond me (with the exception of Baron because he's only 10).
All of these people stick close to him by choice. Children don't have to enter the family business, they can distance themselves from him and his toxic rhetoric and pursue their own endeavors. And Melania married Donald by choice, then continued to stick with him as he proved himself to be a bigot and lech in public many times over.
Occam's razor: It's not some grand selfless act or noble pursuit. She is also just shitty. It's that simple. Same can be said of the kids, Kushner, etc. Again, spare Baron for now because not many kids at 10 will have realized their father is an asshole.