I think most parents attempt to raise our kids to be successful, at least by our own narrow standards. For some parents that means getting them a great education, or indoctrination into the family religion/ business/lifestyle, or getting them to fit in and be popular in a school/neighborhood/office. For some, it simply means arranging that they marry well.
I think the ultimate challenge for all parents is to prepare our child for real life, standing alone, to succeed despite all foreseeable eventualities (death of parents, economic instability, need for self-defense, requiring basic survival skills, etc) while encouraging the child to decide how to define their own success and happiness on their own terms according to their own talents and sense of self.
Ideally, parents must raise children to adulthood within the allotted time period, so that upon their majority they have mastered all the necessary life skills- to get a job, pay their bills, manage their finances, budget a household account, do their taxes, fix their toilet, continue their schooling, and generally navigate the world as a productive and responsible adult.
By adulthood they should control their tempers. modify their behaviors, and keep their activities within legal limits They should be able to set real goals and work hard toward fulfilling their own dreams and desires. They should be able to start, nurture, and maintain good relationships and treat all people fairly and decently. They should have the self-confidence to start their own ventures/businesses/families and captain their own futures.
If an adult child isn't capable of living on his own and doesn't have mental or physical challenges holding them back, then the parents haven't done their jobs. I hear parents say things like "I spoil my teen rotten because (s)he's my baby." and cringe because the last thing we need are more spoiled adult babies who have nothing to offer other people or society in general except the added weight of their burden. Maybe some parents envision being there always to take care of them, but that isn't realistic or healthy or even fair. Parents have to let go and send our kids out into the world so they can be all they can be. It is our job and purpose. If we raised them right, they can soar.
I have raised my son as if I know both his parents are going to drop dead on his 18th birthday. I have no doubt that should that be the case, my son will do great things and have a wonderful life without us.