This is due to the misbehavior of parents who are not good at raising and educating their children. Excessive pampering of wealthy children and the ease with which they obtain everything with complete ease will make them ineligible to bear responsibility themselves and will lead to their bankruptcy after the departure of their wealthy parents.
So the blame is primarily on these rich parents.
I think it is really inappropriate to blame someone who was born into a rich family or was born to parents who were already rich as you mentioned. Because basically everyone in this world is always trying to get rich by always relying on the abilities they already have, so it's really not worth blaming rich parents or a child born into a rich family.
Because as long as the child can become more independent and learn to be responsible by taking advantage of every convenience that already exists in his life, then there is no one to blame for this rich condition. Moreover, I am also quite sure that not all rich people's children are spoiled and also not all poor people's children are hard workers, even though on average poor people's children do have to work hard even though they are forced to endure pain. So don't think that to be good and independent every child must be born into a poor family.