Why would someone continue pumping after weaning?

Hello! I met a woman who pumps a good amount of breastmilk everyday and I just assumed she had little ones at home. Turns out that her youngest is 10 years old (I'm assuming he has to be weaned at this point) - is there a reason to keep pumping after weaning? Is this something I should consider? Would you choose to keep producing milk even after your child is weaned? If so, why?