No parent wants to miss bonding with their child and watching their child grow. You want to be available for your kid during critical life issues and special events.
I have come to realize that adopted children are loved just as much as a natural child and that makes me glad since I have been adopted into God's family.
It can be a large burden for a child to have to undertake a caretaker role that would be expected for someone more in adulthood. You might, in some ways, end up having (the child) sacrifice their opportunity to be a child.