They're never happy for you. It doesn't matter that you've succeeded in something. It doesn't matter that you've reached a major accomplishment. They're just waiting around for the "inevitable" fall.
All news is bad news. Whenever they come to you with some kind of information regarding their life, it's always freaking negative. It's as though they're professional downers. They couldn't be happy if they tried.
They always remind you how bad things will get. There is never a silver lining in their eyes. They're just focused on the negativity. So it makes sense that they'd want to share the fun with you! Which is exactly what they always do.