Checking For Recurring Data That Only Appears In All Columns

Ok I think that i've properly attached the workbook. So as stated, there are four events which comprise the four separate columns. Below the headers are the names of patrons who have attended these events. I want to highlight or distinguish in some way the patrons who bought tickets to all four events. For example, no patron except for "Mike" purchased tickets to all four events. So I want to someway be able to distinguish him from the rest of the data set.