they're not. and if you're asking this question, you're probably underpricing yourself.
do you want to know the secret behind gaining a following and people that will pay for your work?
art does not come easy. it's not as simple as learning to use a cash register or asking if someone wants to upgrade their drink to a large. every time you put down a fellow artist for being able to make a living off their work, you are nullifying the hours, days, years they have spent getting to where they are, which for some, is barely past minimum wage. do you go into walmart to harrass every employee that has the gall to make more than 7.50 an hour? do you go into apple and chide people for buying things you can't afford? no?
then stop shaming artists into underpricing their work, and instead of investing your time in being bitter, jealous, and passive-aggressive, and instead put your energy to use.