I have noticed that perents who in the first place have a fulfilling lives don’t resort to making themselves indispensable to their children.
When parents are satisfied with their own lives, reached self-actualization, are emotionally independent they wouldn’t have the need to make up for themselves from their children lives.
Some parents hold their children responsible for their not having a fulfilling life as a consequence of the sacrifices they made to raise them. So they believe they should be their first priority.
That is why they should start with fixing their own lives in order to stop being emotionally dependent on their children.
I think they should be careful to have their own lives fixed before even having a child. I've seen what resentment does to a parent (though thankfully not my own) and it can be really bad to a child. I agree, most satisfied parents will turn out self-sufficient, happy children. But the trouble is, in our day and age, it's so hard to be content with your job, your partner, who you are in the world (if you do manage to find that out...), so naturally, it's seemingly hard to take good care of your kids too.