Life Experiences

i think the main reason why people may put up with abusive/ toxic parents is because:
1) lack of financial independence
2) nowhere else to go
3) not all abuse is physical or easily spotted. sometimes it can be covert (like parents who are too involved in kids' lives) or simply a parent that neglects their kid by being unavailable/busy all the time
4) they rely on this parents
5) other intimates don't believe the kid or see the abuse as 'normal parenting'
6) the victim is in denial and wants to believe in the love they have for their parents, hoping that things are better than they actually are
7) it may be a difficult situation

and many other reasons too.

thats just my 2 cents i think its unfair to blame the victim.
Leaving is hard, much harder than one would think.
it is so hard to move out nowadays.
(and as for parent who are always busy it is hard to tell if they do it on purpose or not, some parents have to work a lot to feed family)