We have all have something incurable in the future. It’s called death. Do you dread the time ahead of you?
I do.
Well if your already dread the time ahead of you then you might as well know, it can't get much worse eh?
I've known several folks over the years that found peace with their diagnosis, and were able to live their remaining good time with joy and grace. I know I would want to know. FWIW.
If I know I only have N good years left, I can spend all my money instead of dying with it unspent.
It depends on the person, but I'd wager that that perspective isn't even close to the majority one. Death is waiting for everyone, having an actual date range for it doesn't really change _that_ much.
I'd definitely take a different career/life path if I knew I had a few years left. Being able to predict the future has implications on actions.