Equivalent of local idiom "The potter drinks from a broken jar"

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.

The idiom "The shoemaker's children go barefoot" fits. There may be others.

This is a proverb my father, grandpa and grandma (pretty much all of my family members, very often) would use when seeing a person with a profession apply zero to none of their skills for themselves.

I am a Persian descendant, and saying like this are countless.

The famous one and my favorite of is: This too shall pass!

The story comes from an ancient potter who made very beautiful potteries, mostly used for drinking water.

Back them drinking jars made out of clay would keep the water colder than any other jars. the clay would help cool down the water inside, when was wrapped by a moist cloth around it.

The potter himself had a broken one that was at the corner of his store and would use that. he was very busy making pottery fr others, and his would do the job anyways, so why bother.

However in this society this has gone, in some cases to the extreme. For example a psychologist or a life coach who's life is in a total mess, but has helped hundreds to reach phenomenal results.