The rich saying don't go to school is much akin to a beautiful person saying looks don't matter, or a straight person telling their friend to come out to everyone and be their true self. They recognize a truth in the sentiment, but their position and privilege insulates them from the often insurmountable tides that resist the realization of that truth.
School, education... it creates opportunities and cultivates ideas that billionaires either take for granted, or simply discard as useless to someone with functionally infinite resources.