I'm not sure who that would be. We make assumptions every day about what we think other people's lives are like. Maybe they seem successful at work, or to have the perfect marriage or the greatest kids. Maybe they are rolling in money or have a wide circle of friends. But we have no idea what their history really is or how their lives are when no one is looking. We don't know things about mental, physical or sexual abuses they may have suffered. We don't know about closet addictions, affairs, depression and other things that people don't normally talk about. We don't know if the beauty queen will develop cancer or the rich man will go bankrupt.
It is dangerous to spend our lives envying the lives of others and to waste time appreciating what we have ourselves. And if we're dissatisfied with what we have, we should work to change our lives for the better, instead of wishing we had someone's else's life.
When I fantasize about being another person, I don't think about anyone in particular. I think about the attributes that I would like to possess and strive to accomplish those goals. They being, infinite patience, tolerance, intelligence, good humor, and compassion. And yes, superficially, if I had control over things, I would also choose to be drop-dead gorgeous and filthy rich! ( -;