Someone who says "no one wants a needy person" baldly like that with no other explanation to your question is revealing way more about him or herself than about you for asking.

I think the fact that you are asking now about this is a reflection that you are a compassionate person.

But to answer your original query; I have known both: people who came from bad circumstances who are compassionate and kind and people who came from bad circumstances who are cruel and sadistic. I'm guessing it might be a function of temperament and on-going experience (are the circumstances still bad, have they gotten better, etc.) but also of consciously-held values.

Another thing I'd add is that I have known some really egregious people who wanted to insist that they came from Really Wonderful Peachy Keen Circumstances and as far as I was concerned I thought they were either completely clueless about the intersection of behavior and consciousness or they were lying for reasons of their own.

Having supportive people in our lives is a wonderful gift. If someone isn't supportive of me; it is not going to stop me from being supportive of others. I want to be supportive of people; I want to have a joyful life -- a joyful life in the now.

I hope this helps.