There's an idiom in a native language which literally means "The potter drinks from a broken jar".
i.e. a potter will not spend a lot of time making a beautiful jar for himself to drink from, he uses a poor quality one or one that's been broken for himself.
It means that someone who is good at a profession usually sells his high quality work instead of using them for himself and doesn't use them for his own benefit.
Is there an English idiom that conveys the same meaning?
UPDATE
FYI, I was interested in this idiom because my own website consisted of 1 page displaying my email address and saying "We'll have more soon!" during my many years of web development and making websites for others.
Best Answer
The idiom "The shoemaker's children go barefoot" fits. There may be others.