Grow up. To say that Trump has a “very thin skin” is silly. Remember the unreasonable hate that Sarah Palin got in 2008? Trump has much more daily. Good news: underneath hate is fear and screwed up people are fearful of patriotic Americans like Palin and Trump.
Funny that I don't remember Sarah attacking her own people or allies or other Republicans, instead keeping her sights trained squarely on Obama and the Democrats.
Trump just specializes in attacking other Republicans in general, and Conservatives in particular, while buddying up to liberals like Newsome:
The unlikely lovefest between Trump and Newsom: ‘He’s so nice to me’
Other reply to you is correct.
But the other part is that Trump dishes it out constantly. He is an easy target for those “hate” attacks on him. He begs for it. But dishes it out and can’t take it (or at least his lovers can’t take it).
As other poster replied, Palin was not attacking - childishly - other Republicans ever.