Also think about how many people are nostalgic over adventure games and would really love to see a game developer as renown as Double Fine make one. It's perhaps a dream come true for some people... Tim Shafer happened to take advantage of a niche.
Good on him.
For $1,000,000 it'd better be the best damned adventure game ever created, though.
EDIT: And slightly off-topic, speaking of Double Fine, this is interesting.