I'd say bigging yourself up on, or belittling yourself from, others' achievements is a weakness in character and gets in the way of actually producing something worthwhile.

The those who say and those who do have always been around.

The guy in the X tweet isn't bigging up anyone, he's just bringing some people down. And he's hypocritically placing himself firmly in the position of those 'people' he's saying are vile in the actions he's inferring.

Man's a dunce, anyone that votes for him is a dunce and if you don't think so then you ain't black ;p