During Capone's career, he had commited many crimes but the most recognized one is still the St Valentines Day Massacre. Capone could've realized that this mission was a mistake since had spilled the beans to the public. After this event, his crimes were no longer considered personal.
St. Valentines Day Massacre
Capone had ordered this massacre in order to achieve his goal of destroying his enemies s he could take everything and be in control. Capone's gang members as seen at the bottom right are holding machine guns and shotguns ready to fire upon their past enemies. After this massacre happened, I would have believed that Capone might have doubted his actions because of what he had caused to happen to his future self.
(www.mystery.net, St. Valentine's Day Massacre with Pictures - 1929 - Al Capone True Crime Story)
(www.mystery.net, St. Valentine's Day Massacre with Pictures - 1929 - Al Capone True Crime Story)