Let the second author to go to the conference instead of the first author who also wants to go There was a master student who was supervised by a lecturer for his dissertation. They also decided to write and submitted a paper, whose first author was the master student, based on the dissertation. The paper is accepted but it also creates an issue about who should go and present it since there is enough funding for only one person to go to the conference.

The master student wants to go as he is the first author and did most of the work. On the other hand, the lecturer wants to go for networking purposes, e.g. meet other reseachers and find potential collaboration. Moreover, he also reasons that as the student is about to graduate and won't work in academia anymore, it does not have much benefit to fund him to go to the conference.

My question is that whether the lecturer's decision is reasonable.
You're going to get a lot of opinions on this, but I think that if the second author wants to go primarily for networking purposes, he should pay his own way. The student wants to go, did the majority of the work, and is the primary author of the paper. The fact that the student will leave academia after graduating is irrelevant. The student should have his travel paid and present the work at the conference.