People hesitate in donating blood coz of many reasons. First and foremost is the health risks that they are afraid of namely HIV and HCV. They just dont have any confidence in the equipment that our hospitals use.
Secondly new blood is made all the time, whether you donate it or not. Life of an RBC is 120 days. And you really dont get any benefits from your body making new blood. By the time your body makes the new blood cells, you would have already had new blood cells in your body whether you had donated blood or not.
Thirdly, becasue of our cultural, social, work and nutritional habits, generally, our Haemoglobin level is quite alot astray from the norm. So most of you wont know it but are anaemic (low HB).
Fourthly, it isnt very healthy to donate blood at "regular" intervals. You should dontate once every 6 months or so. More than that, do so only in emergencies. Two is the max. More that two and you're risking your health.
And finally, to end on a positive note, the reward you get from Allah, dua you get from the patient (and their family) and self-satisfaction you achieve is what makes us think again (just when we think blood donation isnt the smartest thing in the world). We should think about it before we overlook the situation. What would you want others to do if you were in need?