Perhaps you might reflect on the times that Jesus lived, & existed for 1000,s of years. 

It was the duty of the children to take care of their parents, in their old age. Without the support of the children, the parents would have died. In short, it was a parental death sentence. 

Jesus was condemning the hypocrisy of the Pharisees, but is also noting that the laws to take care of one's parents still stands, as does the punishment to those that ignore that law.