One might argue, that since he's not a career politician, he would be more sensitive to criticism, having not built up a certain amount of resistance over his career.
However, this is Donald Trump, the man is too ignorant, pathetic, and has bullied his way into the public eye for so long, it doesn't hold weight. His grifting and racism have been on full display for almost his entire life and he loves being the centre of attention. His ego, on the other hand, is so fragile, it's weakness.