I said this about Barack Obama in 2009:
It is a mistake to complain about Limbaugh and encourage Republicans not to listen to him. For the leader of the free world to whine about a radio talk show host shows weakness and an inability to take criticism.
This also applies to Donald Trump. Fiercely attacking everyone who criticizes him makes him look weak and thin-skinned. There is a time where is is necessary to defend yourself, of course, but Trump has absolutely no sense of proportion as to when that is needed or when he should let it go.