I'm glad you asked about this question!
Reasoning:
Gary Vee is a marketing genius and he is incredibly influential. His presence here would bring a lot of people to the platform, and he'd likely be able to chime in on how he believes Steemit could market itself better.
Satoshi Nakamoto... I don't think much more reasoning is needed here.
Selena Gomez has more Instagram followers than any other user. Like her or not, she is one of the most influential social media icons, which means she would bring a huge audience with her.
Yes, I totally agree. Every person has his/her own charm and they can add to the community in their own way.
I don't know if someone has directly approached all of them or not?