Most rich people (not super rich) consider themselves middle class. They hang out with other middle class people. Why?
To the extent that they associate with “the same kind of people as they are” the reason is pretty simple, lawyers work in courts and office buildings housing lawyers. Who will they see in the elevators or nearby restaurants? Who will they discuss their cases with? Med doctors work in hospitals and spend their spare moments in buildings housing med operatives. Same diplomats work & socialize with other diplomats.
People of a certain economic classes or professions live in neighbourhoods and join clubs with similar people. Birds of a feather flock together. They can afford and enjoy the same stuff. Golf, tennis, classical music, etc. However, bosses must employ and work with lower income and union people. But socially they are not often interacting. Needless to say, there is not much reason for a successful person to seek friendships with drug addicts or underworld gang members. It could happen, but it would be unusual. Many movies and novels rely upon such odd-couple stories. Alcoholics, thieves, con-men and druggies high-school dropouts may hang out with each other. Some social subgroups like skinheads probably enjoy similar sports, and musical activities. Upper class, productive and successful people are just not fellow travelers in their social milieu. Goldfish don’t swim with sharks, rabbits don’t run with foxes. Birds of a feather flock together.