The advantage of senior developers is that they're more likely to have realistic expectations, do what they do without unnecessarily riding an emotional roller coaster. With experience in any profession it becomes obvious that every project doesn't turn out as imagined.

What is the developer supposed to say about a project that was instigated without their input and without the input of the potential users and is presented up front as a six month slog before reality doubles or triples it? Would, "When it's canceled, I'll mope for a month and come in hung over everyday while looking for another job" be a more inspiring answer?

A better question might have been, what do you think about this idea?