All humans were greedy, it was just a matter of finding out what the person desired most and they would turn out to be greedy for that thing.
Kai Syaoran's words about restoring the sect's past glory made the hearts of the elders and the sect master pump with renewed vigour.
The dream and goal of all the sect higher-ups was to restore the might of the sect and getting the ability to produce Foundation Establishment cultivators like a sow on fertility drugs was a good first step in this direction.
The elders had seen in Kai Syaoran's eyes that no amount of bargaining would make him change his stance and so they capitulated to his demands. Of course, it was also easy for them since they had already discussed the matter before Kai Syaoran showed up and all the other people in the meeting were aware of the sect master plan for the little bastard who dared blackmail the great Heaven Dao sect.