Why do we say that it is obligatory to make up the Hajj of one who invalidated it through intercourse, even though his Hajj was voluntary?

Question : That is, if one invalidates his ritual through intercourse, it becomes obligatory for him to make it up.

Answer : Yes, it is obligatory. Yes, indeed, yes, indeed. And it is not repeated as a voluntary act, because when a person begins Hajj and 'Umrah, it becomes obligatory upon him, binding upon him, and it becomes an individual obligation in his case. This person who took pleasure in his wife has no excuse; he is not like the one who is prevented from completing the pilgrimage. The one who is prevented is only required to make up the obligatory acts, whereas this person invalidated his ritual by his own choice. Is that clear? Yes.