Hopkins lost his first fight, Monzon and Hagler lost early and Hopkins getting a draw with Mercado after two early knockdowns might have been the catalyst to his determination to win the title and defend it 20 times. It's how you come back from defeat that makes you a real champion IMO, Louis did it after Schmeling, Robinson must have been in shock after winning his first 40 fights relatively easily then losing to La Motta, he wouldn't lose again for 8 years and another 90 fights. If you can suck up the defeat and work out what went wrong and make those improvements both physically and mentally then you can come back better than ever. Many great champions have shock losses early or just were not at their best on the night, Jose Napoles lost his 13th and 16th pro fight 6 years before becoming champion, Bob Foster lost to Doug Jones in 8 rounds 6 years before becoming champion (he only really lost to Heavyweights)! Then you have, Alexis Arguello (Fernandez) and Salvador Sanchez (Becerra) who both lost fights unexpectedly. Roberto Duran famously was well beaten by Esteban De Jesus shortly after winning the title at MSG in 1972, it hurt Duran so much he never lost at Lightweight again and wouldn't lose another fight for 8 years. In recent years many champions appear to make a habit of losing after suffering their first loss, Mosley, DLH, Jones Jr (i won't count the DQ), some like Prince Naseem Hamed just turn back into a toad after losing.