Esquire interview
Trump gives his thoughts on dressing well at all times:
I always wear a suit–looking one’s best is good for confidence. High self-esteem is important for effective performance. Dressing well is also a sign of respect, for yourself and for others. I know what I’ll wear every day, which is a suit. It saves time, and I know I’ll look appropriate. I have too much to think about to devote a lot of time to it.