If doing what you love doesn't pay the bills, keep it as a hobby and get a job that does pay the bills. That's part of living in the adult world. Everyone feels worthless from time to time, and most of us really are useless now and then. Your worth isn't based on your usefulness, but many folks think it is. Please understand that your worth as a human doesn't come from anything you do or don't do, or from your abilities, your popularity, what anyone thinks of you, or anything else you can do anything about. All humans have equal worth just because we're humans. Your feelings don't always agree with that, I know, but it is the truth. Don't confuse usefulness and worth.
If your family business is running a workshop, I say you should learn to enjoy that and keep on playing your music, too.