I have a scar from my hair transplant (photo)

I have a scar from my hair transplant, why did it happen, did my doctor do something wrong and what can I do about it? (photo)

You had a strip surgery and clearly scarred worse than many people do. I had three surgeries in the same place and have no significant visible scar. It is not that I had a better surgeon, I just healed better than you did. I am sure your surgeon did the surgery right. The best way to deal with the scar is to have scalp micropigmentation which covers up the scar nicely.  Your picture is on the left, a worst case scar is shown on the right before and after scalp micropigmentation (https://scalpmicropigmentation.com/).  There is hope!