I think this could be one of those situations where those people's self-esteem is so low that they've convinced themselves that meeting new people will result in more heartbreak and rejection. They've become cynical and are probably afraid of meeting new people, and so they 'prefer' staying in that supposed safe zone where although you're sad and lonely, you could be even sadder and more alone and you're not willing to take that risk.
Maybe your best course of action would be to calmly tell them that you know what it's like to feel lonely and rejected, but you feel that if two people who feel that way try to become friends through that common thread, it could be beneficial for both parties.
If they keep pushing you away, tell them 'well, I tried, and there's not much else I can do but I hope you feel better', and try someone else who's more open.