Taylor - it seems like she's trying to be the popular girl in high school. GROW UP.
Katy - sis is over 30. At some point the rainbows and unicorns just get tired. (she's my guilty pleasure tho)
Kanye - acts like a pre-pubescent teen when he doesn't get his way.
Trump - no explanation needed
AB- no explanation needed
And Britney seems like she's still trying to find her adult self. Not really immaturity, but...its hard to explain.
You never see them arguing or dragging people on twitter.
Their very subtle with their shade
You'll never find FULL frontal nudes of them online
They also don't post pics of themselves smoking blunts thinking it's cute.
Their not walking around with steak dresses
Nicki Minaj. Just look at her social media.
The 33 year old threw a tantrum for an entire week last year over some VMA nominations, just to name one of endless immature examples.