Selling one's expertise or talent is a mean quality. Good people will only use their talents in the service of people.
Experts like doctors, lawyers, engineers, chartered accountants, cinema people and many others extract heavy charges from their patients, clients, customers etc for their service. In country like India patients have to shell out such huge sums for hospital expenses that they become paupers finally. These experts do not need so much for their living expenses. But still they collect so much because of their misguided opinions about life. Society's respect for wealth over all other things is the cause for this trend. Certainly this should be considered as mean mindedness.