My ex-boyfriend had it quite noticeably (but not as much as that picture). It had never occurred to him to have something done about it - he only discovered what it was when I was in my 4th year and learning respiratory system examinations!
I have it too, but you can't really tell because my boobs kind of mask it. It's very obvious on X-ray though!
Tbh, my opinion is that getting it fixed would be major, painful surgery. For cosmetic purposes only, I wouldn't say it's worth it unless it's really extreme.