I don't know if you've played the game. There are 4 disease, red, blue, yellow and black. "Curing red" doesn't automatically eliminate the disease - it just makes it easier to deal with, and possible to eliminate in the future (and also is part of the win condition).

Treating people who have a disease right now helps them right now. Curing red has only future benefits.

I now realise you might be asking "how does this demonstrate hyperbolic, as opposed to exponential, discounting", which might be a valid point, but hyperbolic discounting does lead to discounting the future too heavily, so the player's choices do sort of make sense.