Will hair transplant prevent hair from falling out again?

I saw someone who recently had a hair transplant.

It seems you have completely succeeded. Rejuvenation? No, I look like a completely different person. The hair transplant seems to have been successful.

I'm wondering, does it hurt a lot?

How do I wash my hair? How much does it cost?

After doing it, do people who haven't had it done for a while experience hair loss again? Is the results lasting well?

I'm also 고민 because of my 부족한 부분 and want to try ㅠ