Social Origins of the Philosophical Professionalism

You know, those who had been building houses later became architects, and those who had been measuring the lands, fields, and margins turned to geometers. Those who dealt with books like sorting them or classifying them or breaking them into groups later became librarians, and those who cut beards and cut hairs became hairdressers. Those who had been watching the stars, traced them, and named them later turned to astronomers, and those who responded on people's asks, and those who had been controlling people's activities, who had been holding people's funds later became politicians. I wonder who were those ones which turned to philosophers?