Cus he wants help with the jinx not with his actual help
https://www.mangago.zone/read-manga/jinx/uu/br_chapter-196569/pg-35/
" I hired you as my physical therapist"
It more than just his jinx
Rejecting help could be because he is independent and things accepting help or asking for help is a sign of weakness but it is a sign of great strength.
Here he is has a hangover with a nasty headache, bombarded by presents, he seems to hate his birthday, and then he learns why Dan has been acting weird and getting under his skin. He learns Dan went through all that for him, and he just didn't know how to take it. He lashed out.
True that makes sense too, I just assumed he was talking about the jinx cus I didn't think into it much, I assumed "you can easily be replaced" to be more directed to his jinx and them sleeping together (/ telling Dan he wasn't important, just a sex thing) rather than his health because he had just woken up in bed with Dan after getting drunk and saw dan covered in hickeys (+ he aways gave off the impression that the job was just a lie and the only real reason Dan was around was to help his jinx)
damn i forgot out the jinx thing despite it being the title☠
but alr guys i see now thanks
whyd he act like that lmao wasnt he rejecting help from kim dan and now saying hes gotta focus on his work