Are people all the same?
A few days ago, on Facebook, the other members of a group and I, (or myself and some other members of a/my Facebook group) had a discussion on this quote "When you give a lot of importance to someone in your life, you lose your importance in their life." (This would sound better/clearer like this; the more that you give of yourself to someone, the less and less they give back to you. Or. When you give everything to someone, all they do is take and take and give nothing back in return. )

To be honest with you, most of the members completely believed this quote/statement to be true. All of them said that they always try to remember this principle when dealing with others. They believe that there is no exception to this rule; people are all the same and if you give lot of importance (or – give a lot of yourself, or a lot) to someone, you gradually become nothing in their life.
I couldn't and cannot understand their attitude/feelings on this subject. Of course, they might be right, as/because I don't know what they’ve been through and I can't put myself in their shoes. However, in my opinion, there are always some people who break the rules; there is always at the very least one worthwhile person. I don't deny that there are people whose negative reactions to our kindness is heartbreaking, however, I believe that if we keep trying, we'll definitely find someone who appreciates it, and who will return it back to us.

Do you think I live in a fool's paradise?! :)

'Because' I feel may be stronger than ‘as’ in this sentence. ‘...as/because I don't know what...’
You don’t have to put 'at the very least' in, it is fine without it but just may be a stronger emphasis. The same when I put ...’will return it back to us’...