"All Human are naturally greedy and selfish."
Not everyone. Maybe most of them (or a lot of them), but not everyone.
Other than that, I agree with your post. There are a lot of greedy and selfish people on Steemit.
But as you said: "The steem blockchain have the good, the bad and ugly with us here."
So not everyone is greedy and selfish. There are also good and helpful people here, who support the community members.