Ok, imagine this. You for the first time in your life feel like you have energy and strength, only to be told hours later that you are dying from cancer.
Hard to imagine how one would react, I would probably just have given up there and then and never met the fox.
Also the first thing I would have asked the fox is what the price is for the presence increase is, if there is no extra price for the 50 point increase ofc one would go for that. Going for 25 is just stupid, why do he expect to be a side character forever? On the other hand that kind of behavior is quite normal in manga/manhwas for some reason...