Another factor is that you’re probably mostly surveying younger people, who are more likely to have earned a bachelor’s degree. Survey senior citizens and you’ll find that many of them, even people who had successful professional careers, don’t have a bachelor’s, because they weren’t as necessary to secure a good job as they are today. To some extent a bachelor’s has now become what a high school degree was 50 years ago and a graduate degree has become what a college degree once was.
The NCES data show that over 62% of all white students, and 58.7% of students of all races, who started college in 2006 graduated within 6 years. Even over the span of the NCES survey the percentages steadily creep up from 55.4% of all students in 1996 to 58.7% in 2206 and from 58.1% of white students in 1996 to 62.1% in 2006.
You’re also mixing apples and oranges. You cite published statistics for the number of students who have graduated by the age of 23 but you’ve surveyed people who have earned a degree or are on the the way to doing so by the age of 23.