The benifit joint the blood donation activities and why somebody refuse to join this activities?

What exactly is it that someone refuses to join? You need to be more specific to get an answer.

rephrase or add detail to your question.
If some one is sick, has in infection, and disease , or a whole lot of other things that people can get, they can not give blood,
Blood donation is big business. While the average citizen thinks he's doing a good deed by donating his or her blood - and indeed it is a good deed, the benefits are mostly for the company collecting the blood - be it the Red Cross or whatever. These blood banks are in the business of selling your blood to hospitals after they've tested it and they charge a whopping US$500 per pint. You donate and get a popsicle and they get $500! So, who benefits? I think its obvious.