The guy is just talking out of his ass. Tennis is pretty unexpensive. What is expensive, however, is the coaching you need and the relatively high expenses for turning pro and reaching a high level... If you're not super wealthy you might need to be spotted and sponsored/ getting some kind of grant to further advance. But this happens in most competitive individual sports. There's a guy from my hometown my age (name's Galo Blanco), whom I've seen around plenty of times. Plain middle class like me. Guy devoted himself to tennis from an early age. When 15, and after winning couple of tournaments, was sent to a high performance institute run by the Spanish "Consejo Superior de Deportes" and made it to #40 ATP ranking at one time and after retiring helped coaching guys like Raonic, Feliciano López or Andrey Rublev.