I dont believe that Colosimo ever rejected a fat envelope of cash from bootlegging. I know two stories regarding Colosimo's killing...

One was that at first old timers like him or Mont Tennes saw bootlegging as dirty business, same as narcotics and they were quite satisfied with gambling and prostitution. The only old timers that got involved in the booze business at the time, were Jim O'Leary, because of his pharmacy business, and Diamond Joe, because of his sugar business. And story goes that Torrio and Al were already in business with O'Leary and Diamond Joe so i strongly believe that Colosimo took his share from the booze biz.

Now the second story goes that Colosimo got "pussy whipped" by a younger woman, who was the main cause for his quick divorce and also for his quick fall in the underworld. Meaning he did not payed attention to his underlings and always wanted a bigger share. So if you combine the two stories it looks very similar to the Paul Castellano case...